Kidney and Urinary Bladder Stones (Calculi)

Background

Kidney stones are common throughout the world but are more common in industrialized nations. About 5 in 1000 persons are affected with stones of the upper renal urinary tract (kidney) more common than stones in the bladder. The average age of onset is during the thirties. Men are affected with calcium stones more often than women. Recurrences are common and identification of the chemical composition of stones can help in identifying risk factors.

Chemical Composition of Stones Percentage %

Calcium oxalate/Calcium phosphate 75

Magnesium ammonium phosphate 10-15

Uric acid 6

Mixed magnesium, calcium, uric acid 3-10%

Cystine 1-2%

Xanthine Rare

Adenine Rare

There is overlap between the magnesium and uric acid stones since they are frequently mixed with calcium phosphate. It is important to know the pH that each stone precipitates. Calcium oxalate precipitates at acid or neutral pH. Calcium phosphate precipitates at normal urine pH of 6.0-6.5. Uric acid crystallizes at pH 5.3. Magnesium ammonium phosphate forms precipitates at an alkaline pH (pH>7.0). These latter stones are almost always associated with bacterial infections from organisms that can convert urea to ammonia and thus alkalinize the urine. Proteus and some staphylococci are the main offenders. Finally there are rare stones formed by precipitation of various amino acids such as cystine and xanthine, present in patients with inherited defects in amino acid metabolism.

Routine laboratory evaluation includes routine urinalysis with consideration for a 24 hour urine study to urine pH and to quantitate sodium, calcium, phosphorus, uric acid, oxalate, and creatinine clearance. Serum chemistries for the same electrolytes and minerals, chemical analysis of the stone if available, and a radiologic examination are also frequently performed. All stones are radiopaque except pure uric acid and xanthine stones. The pathologist can play an important role in determining the cause of the stones, thus directing preventive therapy.

Outline

Epidemiology
Disease Associations
Pathogenesis
Laboratory/Radiologic/Other Diagnostic Testing
Gross Appearance and Clinical Variants
Prognosis and Treatment
Commonly Used Terms

EPIDEMIOLOGY CHARACTERIZATION

GEOGRAPHY

KOREANS

Prevalence and risk factors of urinary stones in Koreans.

Kim SC, Moon YT, Hong YP, Hwang TK, Choi SH, Kim KJ, Sul CK, Park TC, Kim YG, Park KS.

Department of Urology, College of Medicine, Chung-Ang University, Seoul, Korea.

J Korean Med Sci 1998 Apr;13(2):138-46 Abstract quote

To estimate the prevalence of urinary stone disease in Koreans, and to determine the inter-relationships between urinary stone disease and various epidemiological factors, 1,521 controls and 1,177 cases with urinary stones were evaluated.

Of special interest in this study were: 1) proportion of past urinary stone history among controls; 1.9% 2) the point prevalence rate of urinary stones among controls; 0.2% 3) the recurrence rate of urinary stones (the proportion of past history of urinary stone) among cases; 56.8% 4) high incidences (76.3%) in the thirties to the fifties among cases 5) the risk factors for urolithogenesis; obesity [higher than 25 of BMI (body mass index, weight/height2)], more than 10 year-experience as a production worker, past stone history, familial stone history, low physical activity (< 2,000 Kcal/day), and low intake of fruit.

However, the well-known risk factors for urinary stones; over intake of meat or fish and milk or dairy products, perspiration, amount and kind of drinking water, and stress unexpectedly were not significantly different between the controls and the cases.

DISEASE ASSOCIATIONS CHARACTERIZATION

DIET

Dietary and urinary risk factors for stones in idiopathic calcium stone formers compared with healthy subjects.

Leonetti F, Dussol B, Berthezene P, Thirion X, Berland Y.

Service de Nephrologie, Hopital Sainte Marguerite, Marseille, France.

Nephrol Dial Transplant 1998 Mar;13(3):617-22 Abstract quote

BACKGROUND: The high social-economic cost of nephrolithiasis wholly justifies the attempts to understand its mechanism and avoid recurrences. The influence of dietary habits and urinary risk factors has been evaluated, but the results were discrepant, probably because of differences in the methodologies used to compare patients and controls.

METHODS: The aim was to assess dietary and urinary risk factors for urinary stones by comparison between 108 calcium stone formers (SF) and 210 healthy subjects (HS). All subjects were recruited during the same 1 year period. Personal characteristics, dietary habits (evaluated through a food frequency questionnaire) and urinary biochemical parameters were collected. The high predominance of men in the SF group led us to focus on the 79 SF and the 96 HS men.

RESULTS: A familial history of stones was reported more frequently in SF than in HS, 42.9% vs 17.6%, P<0.005. Body weight was higher in SF, 76.8+/-12.2 kg vs 72.8+/-9.6 kg, P=0.02; and calcium intake was lower in SF, 794.8+/-294.1 mg vs 943.6+/-345.4 mg, P<0.01. For urinary parameters, calcium and oxalate output were significantly higher in SF. Urinary urea, as a reflection of daily protein intake, and uric acid were also higher in SF. Urinary citrate excretion related to body weight was lower in SF. Calciuria was significantly correlated with urinary urea in both SF and HS, but the correlation was stronger for SF. Calciuria correlated significantly with natriuria only in HS.

CONCLUSIONS: The main differences between SF and HS were that SF had a family history of stones, a higher body weight, a lower daily intake of calcium, and a higher urinary output of calcium and oxalate. These results underline the combined role of genetic and nutritional factors in the pathogenesis of urinary stone formation.

RENAL TUBULAR ACIDOSIS

Nephrolithiasis in renal tubular acidosis.

Buckalew VM Jr.

Department of Medicine, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina.

J Urol 1989 Mar;141(3 Pt 2):731-7 Abstract quote

Renal tubular acidosis is a term applied to several conditions in which metabolic acidosis is caused by specific defects in renal tubular hydrogen ion secretion.

Three types of renal tubular acidosis generally are recognized based on the nature of the tubular defect. Nephrolithiasis occurs only in type I renal tubular acidosis, a condition marked by an abnormality in the generation and maintenance of a hydrogen ion gradient by the distal tubule. A forme fruste of type I renal tubular acidosis has been described in which the characteristic defect in distal hydrogen ion secretion occurs in the absence of metabolic acidosis (incomplete renal tubular acidosis). Type I renal tubular acidosis is a heterogeneous disorder that may be hereditary, idiopathic or secondary to a variety of conditions. Secondary type I renal tubular acidosis in sporadic cases is associated most commonly with autoimmune diseases, such as Sjogren's syndrome and systemic lupus erythematosus, and it occurs more frequently in women than men.

Nephrolithiasis, which may occur in any of the subsets of type I renal tubular acidosis, accounts for most of the morbidity in adults and adolescents. Major risk factors for nephrolithiasis include alkaline urine, hypercalciuria and hypocitraturia. In addition, we found hyperuricosuria in 21 per cent of the patients with type I renal tubular acidosis with nephrolithiasis. The most frequently occurring risk factor, hypocitraturia, is due to decreased filtered load and/or to increased tubular reabsorption of filtered citrate. While increased tubular reabsorption may be due to systemic acidosis, hypocitraturia occurs in incomplete renal tubular acidosis. Furthermore, alkali therapy (either bicarbonate or citrate salts) increases citrate excretion in complete and incomplete type I renal tubular acidosis.

These data suggest that hypocitraturia in type I renal tubular acidosis may be due to a defect in proximal tubule function. Hypercalciuria appears to have 2 causes. It may be due to metabolic acidosis, usually in children with a hereditary defect in urine acidification. In other cases familial idiopathic hypercalciuria causes nephrocalcinosis and nephrolithiasis resulting in distal tubular damage and type I renal tubular acidosis. In these latter cases hypercalciuria is present in complete and incomplete type I renal tubular acidosis. Potassium citrate appears to reduce calcium excretion in both types of hypercalciuric type I renal tubular acidosis.

SPINAL CORD INJURY

Bladder stone incidence in persons with spinal cord injury: determinants and trends, 1973-1996.

Chen Y, DeVivo MJ, Lloyd LK.

Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham, Birmingham, Alabama, USA

Urology 2001 Nov;58(5):665-70 Abstract quote

OBJECTIVES: To examine the current trend in the incidence of an initial bladder stone and the potential contributing factors among persons with spinal cord injury.

METHODS: A longitudinal cohort of 1336 patients with spinal cord injury who were injured between 1973 and 1996 and followed up on a yearly basis up to 1999 in a single institution was used to estimate bladder stone incidence. Multivariable analysis was performed to identify risk factors for an initial bladder stone.

RESULTS: During the study period, 229 incident bladder stone cases were documented. It is estimated that for those injured in 1973 to 1979, 1980 to 1984, 1985 to 1989, and 1990 to 1996, the 5-year cumulative incidence rate of an initial bladder stone was 29%, 23%, 14%, and 8%, respectively (P <0.0001). This decreasing trend was consistent for various demographic and clinical characteristics. During the first year after injury only, the bladder stone risk increased with decreasing age (P <0.0001) and was greater for whites. A neurologically complete lesion was associated with an increased bladder stone risk in later years (P = 0.008). Males and persons with indwelling and intermittent catheters had a higher risk during all the years after the injury.

CONCLUSIONS: With improvement in urologic rehabilitation, bladder stone incidence has declined during the past several decades. The study results, however, suggest that new strategic interventions may be required to further prevent stone occurrence in individuals with spinal cord injury and a complete neurologic lesion who are using indwelling catheterization, because these patients are still at a relatively higher risk.

TRANSPLANTATION, KIDNEY

Urinary stones following renal transplantation. Kim H, Cheigh JS, Ham HW.

Dept. of Int. Med., Div. of Nephrology, Sungkyunkwan Univ., School of Med., Kangbuk Samsung Hospital 108, Pyung-Dong, Jongro-Ku, Seoul 110-102, Korea.

Korean J Intern Med 2001 Jun;16(2):118-22 Abstract quote

BACKGROUND: The formation of urinary tract stones following renal transplantation is a rare complication. The clinical features of stones after transplantation differ from those of non-transplant patients. Renal colic or pain is usually absent and rarely resembles acute rejection.

METHODS: We retrospectively studied 849 consecutive kidney transplant patients in The Rogosin Institute/The Weill-Cornell Medical Center, New York who were transplanted between 1980 and 1997 and had functioning grafts for more than 3 months, to determine the incidence of stone formation, composition, risk factors and patient outcome.

RESULTS: At our center, urinary stones were diagnosed in 15 patients (1.8%) of 849 functioning renal grafts for 3 or more months. Of the 15 patients, 10 were males and 5 were females in their third and fourth decade. Eight patients received their transplant from living donors and 7 from cadaveric donors. The stones were first diagnosed between 3 and 109 months after transplantation (mean 17.8 months) and 5 patients had recurrent episodes. The stones were located in the bladder in 11 cases (73.3%), transplanted kidney in 3 cases and in multiple sites in one case. The size of stones varied from 3.4 mm to 40 mm (mean 12 mm). The composition of stones was a mixed form of calcium oxalate and calcium phosphate in 5 cases and 4 patients had infected stones consisting of struvite or mixed form of struvite and calcium phosphate. Factors predisposing to stone formation included tertiary hyperparathyroidism (n = 8), hypercalciuria (n = 5), recurrent urinary tract infection (n = 5), hypocitraturia (n = 4), and obstructive uropathy (n = 2). Many cases had more than one risk factor. Clinically, painless hematuria was observed in 6 patients and dysuria without bacteriuria in 5 patients. None had renal colic or severe pain at any time. There were no changes in graft function at diagnosis and after removal of stones. Five patients passed stones spontaneously and 8 patients underwent cystoscopy for stone removal.

CONCLUSION: Urinary stone formation following kidney transplantation is a rare complication (1.8%). Hyperparathyroidism, hypercalciuria, recurrent urinary tract infection and hypocitraturia are the most common risk factors, but often there are multiple factors which predispose to stone formation. To detect stones and determine their location and size, ultrasonography appears to be the most useful diagnostic tool. Prompt diagnosis, the removal of stones and stone-preventive measures can prevent adverse effects on renal graft outcome.

PATHOGENESIS CHARACTERIZATION

CALCIUM STONES

Study of urinary calcium excretion after oral calcium load in stone formers, their spouses and first-degree blood relatives.

Kaul P, Sidhu H, Vaidyanathan S, Thind SK, Nath R.

Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, India.

Urol Int 1994;52(2):93-7 Abstract quote

Hypercalciuria has long been considered a common abnormality in stone formers, and familial predisposition to renal stone formation has also been reported. Renal stone formers, their spouses and first-degree blood relatives (the latter two groups of subjects had no previous or present history of stone disease) were investigated for their response to an oral load of 2 g calcium (as di-calcium phosphate).

Serum calcium, phosphorus, uric acid, creatinine and urea were within the normal range in all the subjects initially as well as 4 h after the load. After the oral calcium load, 66.6% of the stone formers, 25% of the first-degree relatives and none of the spouses were hypercalciuric. Administration of 2 g calcium produced a significantly greater urinary excretion of calcium in stone formers (123.8 +/- 43 mg/8 h, p < 0.001) and their first-degree blood relatives (89.8 +/- 26 mg/8 h, p < 0.01) as compared to the spouses of stone formers (65.5 +/- 12.8 mg/8 h). A significant increase in urinary calcium excretion after calcium loading was also found among the stone formers (p < 0.01) as compared to their first-degree blood relatives.

A significantly higher mean rise in calcium excretion (over the basal excretion) in calcium stone formers (p < 0.001) and their first-degree blood relatives (p < 0.01), as compared to the spouses of stone formers suggests a greater predisposition to renal stone disease in first-degree blood relatives than the spouses of the stone patients

FIBRONECTIN

Comparison of fibronectin content in urinary macromolecules between normal subjects and recurrent stone formers.

Tsujihata M, Miyake O, Yoshimura K, Kakimoto K, Takahara S, Okuyama A.

Department of Urology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.

Eur Urol 2001 Oct;40(4):458-62 Abstract quote

OBJECTIVES: Fibronectin (FN: 230 kD) is a multifunctional alpha(2)-glycoprotein distributed throughout the extracellular matrix and body fluids. Recent studies have shown that a variety of molecules, including FN, inhibit the endocytosis of calcium oxalate (CaOx) crystals in vitro. We recently reported that FN was oversecreted from the renal tubular cells as a result of the stimulation of CaOx crystals, and inhibited the aggregation of CaOx crystals and the adhesion of CaOx crystals to the renal tubular cells. In the present study, we investigated the difference of FN content in urinary macromolecules (UMMs) between normal subjects and recurrent stone formers.

MATERIALS AND METHODS: Urinary parameters in relation to urolithiasis of normal subjects and recurrent stone formers were measured. Proteins in extracted UMMs from urine of normal subjects and recurrent stone formers were measured with a BioRad protein assay, GAGs in each UMMs with a modified DMB assay and the FN content with the ELISA method.

RESULTS: In urinary parameters, citrate was significantly higher in urine from normal subjects (female) than normal subjects (male) or recurrent stone formers, and the other parameters showed no differences between each group. The protein concentrations in UMMs showed no differences between each group. Normal subjects (male and female) showed a significantly higher concentration of GAGs than recurrent stone formers (with and without silent stone). Compared with normal subjects and recurrent stone formers without silent stones, higher FN levels were found in recurrent stone formers with silent stones. Normal subjects showed a significantly higher concentration of FN than recurrent stone formers without silent stones. No difference in FN level was shown between normal subjects (male) and normal subjects (female).

CONCLUSION: Recurrent stone formers with silent stones showed a significantly higher concentration of FN in UMMs than normal subjects. This finding suggests that FN might be oversecreted from the renal tubular cells as a result of the stimulation of CaOx stones in vivo. Recurrent stone formers without silent stones showed a significantly lower concentration of FN in UMMs than normal subjects. From this finding it is suggested that FN might play a role as a potent inhibitor of CaOx urolithiasis in a clinical setting.

INDINAVIR

Urinary Cytology Associated With Human Polyomavirus and Indinavir Therapy in HIV-Infected Patients

Armando C. Filie, MD, Anna Maria Wilder, CT(ASCP), Keith Brosky, CT(ASCP), Jeffrey B. Kopp, MD, Kirk D. Miller, MD, and Andrea Abati, MD

Am J Clin Pathol 2002;117:922-926 Abstract quote

We retrospectively analyzed 155 urine cytology samples (78 from patients treated with indinavir; 77, no indinavir) from 90 HIV+ patients to evaluate possible association between human polyomavirus and hematuria and to describe indinavir-associated urinary cytologic findings. The CD4 count also was recorded.

Variables studied included the presence of cellular viral changes consistent with polyomavirus infection (PVCs), microscopic hematuria, multinucleated cells, indinavir crystals, neutrophils, and eosinophils. Twenty-two samples (15.8%) from patients with CD4 counts of more than 200/µL (>200 × 106/L) showed PVCs. Multinucleated cells, of presumed histiocytic origin based on morphologic features and selective immunocytochemical findings, were present in a higher percentage of samples from indinavir-treated patients. Neutrophils were present in a higher percentage of indinavir-treated patients. Indinavir crystals were identified in 9 samples (12%) from patients receiving indinavir. The lower percentage of PVCs in HIV+ patients with high CD4 counts likely represents an indirect antipolyomavirus indinavir effect by boosting immunity. Multinucleated cells (presumably histiocytic) and acute inflammation are associated with indinavir therapy.

Indinavir crystals have a characteristic fan or circular lamellate appearance. Because indinavir crystals may be associated with genitourinary disease, recognizing and reporting them is clinically relevant in HIV+ patients.

NANOBACTERIA

URIC ACID STONES

Identification of a new candidate locus for uric acid nephrolithiasis.

Ombra MN, Forabosco P, Casula S, Angius A, Maestrale G, Petretto E, Casu G, Colussi G, Usai E, Melis P, Pirastu M.

Istituto di Genetica Molecolare, CNR, 07040 Santa Maria La Palma (SS), Italy.

Am J Hum Genet 2001 May;68(5):1119-29 Abstract quote

Renal stone formation is a common multifactorial disorder, of unknown etiology, with an established genetic contribution. Lifetime risk for nephrolithiasis is approximately 10% in Western populations, and uric acid stones account for 5%-10% of all stones, depending on climatic, dietary, and ethnic differences.

We studied a small, isolated founder population in Sardinia, characterized by an increased prevalence of uric acid stones, and performed a genomewide search in a deep-rooted pedigree comprising many members who formed uric acid renal stones. The pedigree was created by tracing common ancestors of affected individuals through a genealogical database based on archival records kept by the parish church since 1640. This genealogical information was used as the basis for the study strategy, involving screening for alleles shared among affected individuals, originating from common ancestors, and utilization of large pedigrees to obtain greater power for linkage detection. We performed multistep linkage and allele-sharing analyses. In the initial stage, 382 markers were typed in 14 closely related affected subjects; interesting regions were subsequently investigated in the whole sample.

We identified two chromosomal regions that may harbor loci with susceptibility genes for uric acid stones. The strongest evidence was observed on 10q21-q22, where a LOD score of 3.07 was obtained for D10S1652 under an affected-only dominant model, and a LOD score of 3.90 was obtained using a dominant pseudomarker assignment. The localization was supported also by multipoint allele-sharing statistics and by haplotype analysis of familial cases and of unrelated affected subjects collected from the isolate. In the second region on 20q13.1-13.3, multipoint nonparametric scores yielded suggestive evidence in a approximately 20-cM region, and further analysis is needed to confirm and fine-map this putative locus. Replication studies are required to investigate the involvement of these regions in the genetic contribution to uric acid stone formation.

LABORATORY/RADIOLOGIC/
OTHER TESTS
CHARACTERIZATION

RADIOLOGIC

CT

Computed tomography versus intravenous urography in diagnosis of acute flank pain from urolithiasis: a randomized study comparing imaging costs and radiation dose.

Thomson JM, Glocer J, Abbott C, Maling TM, Mark S.

Department of Radiology, Christchurch Hospital, Christchurch, New Zealand.

Australas Radiol 2001 Aug;45(3):291-7 Abstract quote

The equivalent sensitivity of non-contrast computed tomography (NCCT) and intravenous urography (IVU) in the diagnosis of suspected ureteric colic has been established. Approximately 50% of patients with suspected ureteric colic do not have a nephro-urological cause for pain. Because many such patients require further imaging studies, NCCT may obviate the need for these studies and, in so doing, be more cost effective and involve less overall radiation exposure.

The present study compares the total imaging cost and radiation dose of NCCT versus IVU in the diagnosis of acute flank pain. Two hundred and twenty-four patients (157 men; mean age 45 years; age range 19-79 years) with suspected renal colic were randomized either to NCCT or IVU. The number of additional diagnostic imaging studies, cost (IVU A$136; CTU A$173), radiation exposure and imaging times were compared. Of 119 (53%) patients with renal obstruction, 105 had no nephro-urological causes of pain. For 21 (20%) of these patients an alternative diagnosis was made at the initial imaging, 10 of which were significant.

Of 118 IVU patients, 28 (24%) required 32 additional imaging tests to reach a diagnosis, whereas seven of 106 (6%) NCCT patients required seven additional imaging studies. The average total diagnostic imaging cost for the NCCT group was A$181.94 and A$175.46 for the IVU group (P < 0.43). Mean radiation dose to diagnosis was 5.00 mSv (NCCT) versus 3.50 mSv (IVU) (P < 0.001). Mean imaging time was 30 min (NCCT) versus 75 min (IVU) (P < 0.001). Diagnostic imaging costs were remarkably similar.

Although NCCT involves a higher radiation dose than IVU, its advantages of faster diagnosis, the avoidance of additional diagnostic imaging tests and its ability to diagnose other causes makes it the study of choice for acute flank pain at Christchurch Hospital.

Ultrasound vs CT for the detection of ureteric stones in patients with renal colic.

Patlas M, Farkas A, Fisher D, Zaghal I, Hadas-Halpern I.

Department of Radiology, Shaare Zedek Medical Center, Jerusalem 91031, Israel.

Br J Radiol 2001 Oct;74(886):901-4 Abstract quote

The aim of our study was to compare the accuracy of non-contrast spiral CT with ultrasound (US) for the diagnosis of ureteral calculi in the evaluation of patients with acute flank pain.

62 consecutive patients with flank pain were examined with both CT and US over a period of 9 months. All patients were prospectively defined as either positive or negative for ureterolithiasis, based on follow-up evaluation. 43 of the 62 patients were confirmed as having ureteral calculi based on stone recovery or urological interventions. US showed 93% sensitivity and 95% specificity in the diagnosis of ureterolithiasis; CT showed 91% and 95%, respectively. Pathology unrelated to urinary stone disease was demonstrated in six patients.

Although both modalities were excellent for detecting ureteral stones, consideration of cost and radiation lead us to suggest that US be employed first and CT be reserved for when US is unavailable or non-diagnostic.

CT urograms in pediatric patients with ureteral calculi: do adult criteria work?

Smergel E, Greenberg SB, Crisci KL, Salwen JK.

Department of Radiology, St. Christopher's Hospital for Children, Erie Avenue at Front Street, Philadelphia, PA 19134, USA.

Pediatr Radiol 2001 Oct;31(10):720-3 Abstract quote

BACKGROUND: Secondary signs of urinary obstruction associated with ureteral calculi are useful adjuncts to diagnosis in adults with renal colic evaluated by unenhanced helical CT.

OBJECTIVE: Our purpose was to evaluate the frequency of secondary signs of obstruction in children with renal colic undergoing unenhanced helical CT.

MATERIALS AND METHODS: Ureteral calculi were identified in 20 of 61 children with acute flank pain examined by unenhanced helical CT. Each imaging study was evaluated for the presence of secondary signs of urinary obstruction. The frequencies of individual signs were compared with each other by means of the McNemar test.

RESULTS: Six children had no secondary sign identified. In the remaining 14 children, proximal ureteral dilatation was seen in 10, renal enlargement in 10, hydronephrosis in 9, tissue rim sign in 6, decreased kidney attenuation in 5, and perinephric stranding in 1. Comparison of the frequencies strongly suggested that perinephric stranding occurs less frequently than proximal ureteral dilatation (P = 0.004), hydronephrosis (P = 0.008), or renal enlargement (P = 0.012).

CONCLUSION: Perinephric stranding, a common secondary sign in adults with ureteral calculi, occurs less frequently in children than other reported secondary signs.

Value of multislice helical CT scans and maximum-intensity-projection images to improve detection of ureteral stones at abdominal radiography.

Van Beers BE, Dechambre S, Hulcelle P, Materne R, Jamart J.

Department of Radiology, Universite Catholique de Louvain, Saint-Luc University Hospital, Ave. Hippocrate 10, B-1200 Brussels, Belgium.

AJR Am J Roentgenol 2001 Nov;177(5):1117-21 Abstract quote

OBJECTIVE: The purpose of this study was to assess the improvement in the detection of ureteral stones on abdominal radiographs when the stones were viewed on multislice helical CT scans and maximum-intensity-projection (MIP) images.

SUBJECTS AND METHODS: The study included 72 patients with renal colic who underwent abdominal radiography and multislice helical CT. For each patient, a frontal MIP image was generated, and the stone, when present, was marked with a cross on the transverse CT scan. The cross appeared automatically on the corresponding MIP image. The CT examination was used as the standard of reference. The presence and location of ureteral stones on the abdominal radiographs were assessed during three interpretation sessions. In the first session, the abdominal radiographs were viewed alone. In the second, they were viewed with the transverse CT scans. In the third, the abdominal radiographs were viewed with the CT scans and the MIP images.

RESULTS: Ureteral stones were present in 58 patients. The percentage of stones detected on the abdominal radiographs was 45% when the radiographs were viewed alone, 66% when they were viewed with the CT scans (p = 0.002 vs radiographs alone), and 78% when viewed with the CT scans and MIP images (p = 0.016 vs radiographs with CT scans).

CONCLUSION: The sensitivity of stone detection on abdominal radiographs was greatest when the interpreters viewed the radiographs in conjunction with the CT scans and MIP images.

LABORATORY MARKERS

The preservation of urine samples for determination of renal stone risk factors.

Nicar MJ, Hsu MC, Johnson T, Pak CY.

Center on Mineral Metabolism and Clinical Research, Southwestern Medical School of the University of Texas Health Science Center at Dallas, TX 75235, USA.

Lab Med 1987 Jun;18(6):382-4 Abstract quote

A preservation technique for urine specimens before determination of stone risk factors was evaluated.

The purpose of these experiments was to prove the effectiveness of the preservatives used to prevent changes in the concentrations of those constituents measured. Measured concentrations in fresh specimens were compared with those in the same specimens after storage with the preservatives.

Refrigeration at 4 degrees C up to five days was appropriate in a laboratory setting, as no significant changes in urinary concentrations occurred. Refrigeration, however, did not offer a convenient method for shipping. Chemical preservation was found to be an effective alternative to refrigeration. Thymol prevented changes in concentration of pH, citrate, uric acid, sulfate, sodium, potassium, and cyclic AMP, while a mixture of hydrochloric (HCl) acid and boric acid prevented changes in calcium, magnesium, phosphorus, oxalate, ammonium, and creatinine.

Thus, the addition of thymol or HCl/boric acid to urine specimens will prevent significant changes in the concentrations of stone risk factors.

REPORTING

Integration of Text, Image, and Graphic Data From Different Sources in Laboratory Reports
Example of Kidney Stone Reporting System

Shang-Che Lin, MBA, MS
Frederick Van Lente, PhD
Adam Fadlalla, PhD
Walter H. Henricks, MD
Am J Clin Pathol 2002;118:179-183 Abstract quote

Laboratory analyses may generate multiple data types that may reside in disparate systems, and combining data into a report often requires laborious, error-prone methods. Kidney stone analysis, which includes biochemical composition analysis and gross feature documentation, is an example of such a situation.
We developed the kidney stone reporting system (KISS) that integrates patient and specimen information from the laboratory information system, digital images of stones, and analytic instrument data into a concise report for the ordering clinicians. The database management environment facilitates archival and retrieval capabilities. Implementation of the system has reduced the number of manual steps necessary to produce a report and has saved approximately 30 technologist hours per week. Transcription errors have been virtually eliminated.

The KISS represents an innovative use of standard tools to integrate text, image, and graphic data from disparate systems into an integrated laboratory report, without the need for expensive interfaces.

GROSS APPEARANCE/
CLINICAL VARIANTS CHARACTERIZATION

GENERAL

VARIANTS

FAMILIAL

Idiopathic hypercalciuria and hyperuricosuria: family prevalence of nephrolithiasis.

Polito C, La Manna A, Nappi B, Villani J, Di Toro R.

Clinica Pediatrica III, Naples, Italy.

Pediatr Nephrol 2000 Oct;14(12):1102-4 Abstract quote

We studied the prevalence of a history of nephrolithiasis in first- and second-degree relatives of 74 children with hypercalciuria (HC), 61 with hyperuricosuria (HU), and 41 with HC plus HU, and in a control population of 261 children with different diseases.

Family history of nephrolithiasis was found in 69% of HC, 75% of HU, 78% of HC plus HU, and 22% of control patients. The prevalence was not different among HC, HU, and HC plus HU groups, but was significantly higher in each study group than the control group (P=0.0001). Body mass index >95th percentile was found in only 4.7% of the patients with HC or HC plus HU. Calculi (>3 mm in diameter) were present in 8.9% of the patients with a family history of nephrolithiasis and in 9.4% of those with no family history (P=0.85).

Microcalculi (<3 mm in diameter) were found by sonography in 56.6% of the patients with and in 53.3% of those without a family history of nephrolithiasis (P=0.83). Children with HC and/or HU have a strong familial prevalence of nephrolithiasis. Obesity does not seem to affect the association of familial nephrolithiasis and hypercalciuria in children. The presence of nephrolithiasis in families of children with HC and/or HU is not associated with a higher rate of formation of calculi or microcalculi.

PROGNOSIS AND TREATMENT CHARACTERIZATION

PROGNOSTIC FACTORS

TREATMENT

GENERAL

DISTAL STONES

Prospective randomized trial comparing shock wave lithotripsy and ureteroscopy for management of distal ureteral calculi.

Pearle MS, Nadler R, Bercowsky E, Chen C, Dunn M, Figenshau RS, Hoenig DM, McDougall EM, Mutz J, Nakada SY, Shalhav AL, Sundaram C, Wolf JS Jr, Clayman RV.

Department of Urology, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.

J Urol 2001 Oct;166(4):1255-60 Abstract quote

PURPOSE: We compared the efficacy of shock wave lithotripsy and ureteroscopy for treatment of distal ureteral calculi.

MATERIALS AND METHODS: A total of 64 patients with solitary, radiopaque distal ureteral calculi 15 mm. or less in largest diameter were randomized to treatment with shock wave lithotripsy (32) using an HM3 lithotriptor (Dornier MedTech, Kennesaw, Georgia) or ureteroscopy (32). Patient and stone characteristics, treatment parameters, clinical outcomes, patient satisfaction and cost were assessed for each group.

RESULTS: The 2 groups were comparable in regard to patient age, sex, body mass index, stone size, degree of hydronephrosis and time to treatment. Procedural and operating room times were statistically significantly shorter for the shock wave lithotripsy compared to the ureteroscopy group (34 and 72 versus 65 and 97 minutes, respectively). In addition, 94% of patients who underwent shock wave lithotripsy versus 75% who underwent ureteroscopy were discharged home the day of procedure. At a mean followup of 21 and 24 days for shock wave lithotripsy and ureteroscopy, respectively, 91% of patients in each group had undergone imaging with a plain abdominal radiograph, and all studies showed resolution of the target stone. Minor complications occurred in 9% and 25% of the shock wave lithotripsy and ureteroscopy groups, respectively (p value was not significant). No ureteral perforation or stricture occurred in the ureteroscopy group. Postoperative flank pain and dysuria were more severe in the ureteroscopy than shock wave lithotripsy group, although the differences were not statistically significant. Patient satisfaction was high, including 94% for shock wave lithotripsy and 87% for ureteroscopy (p value not significant). Cost favored ureteroscopy by $1,255 if outpatient treatment for both modalities was assumed.

CONCLUSIONS: Ureteroscopy and shock wave lithotripsy were associated with high success and low complication rates. However, shock wave lithotripsy required significantly less operating time, was more often performed on an outpatient basis, and showed a trend towards less flank pain and dysuria, fewer complications and quicker convalescence. Patient satisfaction was uniformly high in both groups. Although ureteroscopy and shock wave lithotripsy are highly effective for treatment of distal ureteral stones, we believe that HM3 shock wave lithotripsy, albeit slightly more costly, is preferable to manipulation with ureteroscopy since it is equally efficacious, more efficient and less morbid.

EXTRACORPOREAL SHOCK-WAVE LITHOTRIPSY

Extracorporeal shock-wave lithotripsy: a comparative study of electrohydraulic and electromagnetic units.

Matin SF, Yost A, Streem SB.

Urological Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA

J Urol 2001 Dec;166(6):2053-6 Abstract quote

PURPOSE: We determined the results of shock wave lithotripsy with a newer electromagnetic lithotriptor and compared them with those in a contemporary series of cases managed by an electrohydraulic lithotriptor using identical treatment and followup criteria at a single center.

MATERIALS AND METHODS: Between 1995 and 1999, 356 patients (375 renal units, 483 upper urinary tract stones) meeting study inclusion criteria were treated with an MFL 5000 electrohydraulic shock wave lithotripsy unit (Dornier Medical Systems, Inc., Marietta, Georgia). From 1999 to 2000, 173 patients (175 renal units; 218 upper urinary tract stones) meeting identical study inclusion criteria were treated using an electromagnetic Modulith SLX shock wave lithotripsy unit (Karl Storz Lithotripsy, Atlanta, Georgia). In each group stone-free results were determined by plain abdominal x-ray and renal ultrasound 1 month after lithotripsy and efficiency quotients were developed. Baseline patient and stone characteristics were compared by the Wilcoxon rank sum and Fisher exact tests. All variables significant at p <0.05 were included in subsequent outcome analysis using multivariate logistic regression.

RESULTS: Baseline characteristics were equivalent, including patient age, gender, stone number and location, although patients treated with the electrohydraulic unit had a significantly larger median stone burden (103 versus 71 mm.2, p = 0.015). Multivariate regression analysis demonstrated a higher stone-free rate in the electrohydraulic group (77% versus 67%, p = 0.01) but also a higher rate of total adjunctive measures (56% versus 47%, p = 0.04). Consequently the efficiency quotients were comparable for the electrohydraulic and electromagnetic lithotripsy units (0.45 and 0.42, respectively, p = 0.43).

CONCLUSIONS: Electrohydraulic lithotripsy resulted in a higher stone-free rate at 1 month, although it was associated with a higher rate of auxiliary measures. Ultimately the efficiency quotients were equivalent, implying that these 2 contemporary energy sources are acceptable. According to single center treatment and followup criteria they are equally efficacious.

LOWER POLE STONES

Mechanical percussion, inversion and diuresis for residual lower pole fragments after shock wave lithotripsy: a prospective, single blind, randomized controlled trial.

Pace KT, Tariq N, Dyer SJ, Weir MJ, D'A Honey RJ.

St. Michael's Hospital, University of Toronto, Ontario, Canada.

J Urol 2001 Dec;166(6):2065-71 Abstract quote

PURPOSE: We compare the effectiveness of mechanical percussion and inversion with observation for eliminating lower caliceal fragments 3 months after shock wave lithotripsy.

MATERIALS AND METHODS: At 3 months after shock wave lithotripsy 69 patients with residual lower caliceal fragments 4 mm. or less were randomized to receive either mechanical percussion and inversion or observation for 1 month. The observation group then received crossover mechanical percussion and inversion if fragments persisted. All patients were followed with plain film of the kidneys, ureters and bladder to assess the stone area and stone-free status, and renal tomography or noncontrast spiral computerized tomography to confirm stone-free status. A blinded radiologist reviewed all films. Patients were treated with a mechanical chest percussor applied to the flank while inverted to greater than 60 degrees after receiving 20 mg. furosemide.

RESULTS: A total of 35 patients were randomized to receive immediate mechanical percussion and inversion therapy and 34 observation. Of the patients in the observation group 28 subsequently received mechanical percussion and inversion after completing the observation period. The groups were not different in gender, body mass index, side affected, stone location or renal anatomical features. The mechanical percussion and inversion group had a substantially higher stone-free rate than the observation group (40% versus 3%, respectively, p <0.001). The mechanical percussion and inversion group also had a greater improvement in total stone area than controls (-63.3% versus +2.7%, respectively, p <0.001). No significant adverse effects were noted in the mechanical percussion and inversion group.

CONCLUSIONS: Mechanical percussion and inversion is a safe and effective treatment option for residual lower caliceal fragments 3 months after shock wave lithotripsy. Nearly 50% of patients become stone-free, and stone burden is decreased by 50% in the remainder.

Lower pole I: a prospective randomized trial of extracorporeal shock wave lithotripsy and percutaneous nephrostolithotomy for lower pole nephrolithiasis-initial results.

Albala DM, Assimos DG, Clayman RV, Denstedt JD, Grasso M, Gutierrez-Aceves J, Kahn RI, Leveillee RJ, Lingeman JE, Macaluso JN Jr, Munch LC, Nakada SY, Newman RC, Pearle MS, Preminger GM, Teichman J, Woods JR.

J Urol 2001 Dec;166(6):2072-80 Abstract quote

PURPOSE: The efficacy of shock wave lithotripsy and percutaneous stone removal for the treatment of symptomatic lower pole renal calculi was determined.

MATERIALS AND METHODS: A prospective randomized, multicenter clinical trial was performed comparing shock wave lithotripsy and percutaneous stone removal for symptomatic lower pole only renal calculi 30 mm. or less.

RESULTS: Of 128 patients enrolled in the study 60 with a mean stone size of 14.43 mm. were randomized to percutaneous stone removal (58 treated, 2 awaiting treatment) and 68 with a mean stone size of 14.03 mm. were randomized to shock wave lithotripsy (64 treated, 4 awaiting treatment). Followup at 3 months was available for 88% of treated patients. The 3-month postoperative stone-free rates overall were 95% for percutaneous removal versus 37% lithotripsy (p <0.001). Shock wave lithotripsy results varied inversely with stone burden while percutaneous stone-free rates were independent of stone burden. Stone clearance from the lower pole following shock wave lithotripsy was particularly problematic for calculi greater than 10 mm. in diameter with only 7 of 33 (21%) patients becoming stone-free. Re-treatment was necessary in 10 (16%) lithotripsy and 5 (9%) percutaneous cases. There were 9 treatment failures in the lithotripsy group and none in the percutaneous group. Ancillary treatment was necessary in 13% of lithotripsy and 2% percutaneous cases. Morbidity was low overall and did not differ significantly between the groups (percutaneous stone removal 22%, shock wave lithotripsy 11%, p =0.087). In the shock wave lithotripsy group there was no difference in lower pole anatomical measurements between kidneys in which complete stone clearance did or did not occur.

CONCLUSIONS: Stone clearance from the lower pole following shock wave lithotripsy is poor, especially for stones greater than 10 mm. in diameter. Calculi greater than 10 mm. in diameter are better managed initially with percutaneous removal due to its high degree of efficacy and acceptably low morbidity.

PERCUTANEOUS NEPHROLITHOTOMY

Prospective randomized study of various techniques of percutaneous nephrolithotomy.

Feng MI, Tamaddon K, Mikhail A, Kaptein JS, Bellman GC.

Department of Urology, Kaiser Permanente Medical Center, Los Angeles, California 900247, USA

Urology 2001 Sep;58(3):345-50 Abstract quote

OBJECTIVES: To compare the modifications of the technique of percutaneous nephrolithotomy (PCN), including "mini-PCN" and tubeless PCN, to establish which technique is associated with the least morbidity and complications.

METHODS: We performed a prospective randomized trial to assess the efficacy and morbidity of each method of percutaneous renal access. Standard PCN involved tract dilation to 30F for passage of a 34F working sheath, and our "mini-PCN" involved tract dilation to 22F for passage of a 26F sheath. Tubeless PCN involved the use of a double-J stent for internal drainage without the use of a nephrostomy tube for external drainage at termination of the procedure. Thirty patients (10 patients in each group) were enrolled, and 27 patients completed the study. All three groups were compared with regard to postoperative pain using a validated pain questionnaire comprised of a visual analogue scale and a verbal rating scale. The operative time, estimated blood loss, stone burden, procedure success rate, stone-free rate, length of hospitalization, total procedural cost, and complications were also compared for each technique.

RESULTS: The tubeless PCN population required less morphine use, had a decreased length of hospitalization, and had a smaller total procedural cost compared with the other two groups. One complication was noted in both the standard and mini-PCN groups, consisting of renal bleeding requiring a 2 and 3-U blood transfusion in the standard and mini-PCN groups, respectively.

CONCLUSIONS: The tubeless technique is associated with the least amount of morbidity and the greatest cost efficiency compared with the other techniques. No overall advantage was found for the mini-PCN versus the standard technique, but the mini-PCN is at a slight disadvantage because of poorer visualization and optics and difficulty with use of the nephroscopic graspers.

Henry JB. Clinical Diagnosis and Management by Laboratory Methods. Twentieth Edition. WB Saunders. 2001.
Rosai J. Ackerman's Surgical Pathology. Eight Edition. Mosby 1996.
Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.

Commonly Used Terms

Staghorn calculi -Large bulky stones formed in the renal pelvis, almost always a result of infection by certain bacteria such as Proteus and some staphylococci.

U/A-Urinalysis.

Last Updated 8/5/2002

DISEASE ASSOCIATIONS	CHARACTERIZATION
DIET
Dietary and urinary risk factors for stones in idiopathic calcium stone formers compared with healthy subjects. Leonetti F, Dussol B, Berthezene P, Thirion X, Berland Y. Service de Nephrologie, Hopital Sainte Marguerite, Marseille, France.	Nephrol Dial Transplant 1998 Mar;13(3):617-22 Abstract quote BACKGROUND: The high social-economic cost of nephrolithiasis wholly justifies the attempts to understand its mechanism and avoid recurrences. The influence of dietary habits and urinary risk factors has been evaluated, but the results were discrepant, probably because of differences in the methodologies used to compare patients and controls. METHODS: The aim was to assess dietary and urinary risk factors for urinary stones by comparison between 108 calcium stone formers (SF) and 210 healthy subjects (HS). All subjects were recruited during the same 1 year period. Personal characteristics, dietary habits (evaluated through a food frequency questionnaire) and urinary biochemical parameters were collected. The high predominance of men in the SF group led us to focus on the 79 SF and the 96 HS men. RESULTS: A familial history of stones was reported more frequently in SF than in HS, 42.9% vs 17.6%, P<0.005. Body weight was higher in SF, 76.8+/-12.2 kg vs 72.8+/-9.6 kg, P=0.02; and calcium intake was lower in SF, 794.8+/-294.1 mg vs 943.6+/-345.4 mg, P<0.01. For urinary parameters, calcium and oxalate output were significantly higher in SF. Urinary urea, as a reflection of daily protein intake, and uric acid were also higher in SF. Urinary citrate excretion related to body weight was lower in SF. Calciuria was significantly correlated with urinary urea in both SF and HS, but the correlation was stronger for SF. Calciuria correlated significantly with natriuria only in HS. CONCLUSIONS: The main differences between SF and HS were that SF had a family history of stones, a higher body weight, a lower daily intake of calcium, and a higher urinary output of calcium and oxalate. These results underline the combined role of genetic and nutritional factors in the pathogenesis of urinary stone formation.
RENAL TUBULAR ACIDOSIS
Nephrolithiasis in renal tubular acidosis. Buckalew VM Jr. Department of Medicine, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina.	J Urol 1989 Mar;141(3 Pt 2):731-7 Abstract quote Renal tubular acidosis is a term applied to several conditions in which metabolic acidosis is caused by specific defects in renal tubular hydrogen ion secretion. Three types of renal tubular acidosis generally are recognized based on the nature of the tubular defect. Nephrolithiasis occurs only in type I renal tubular acidosis, a condition marked by an abnormality in the generation and maintenance of a hydrogen ion gradient by the distal tubule. A forme fruste of type I renal tubular acidosis has been described in which the characteristic defect in distal hydrogen ion secretion occurs in the absence of metabolic acidosis (incomplete renal tubular acidosis). Type I renal tubular acidosis is a heterogeneous disorder that may be hereditary, idiopathic or secondary to a variety of conditions. Secondary type I renal tubular acidosis in sporadic cases is associated most commonly with autoimmune diseases, such as Sjogren's syndrome and systemic lupus erythematosus, and it occurs more frequently in women than men. Nephrolithiasis, which may occur in any of the subsets of type I renal tubular acidosis, accounts for most of the morbidity in adults and adolescents. Major risk factors for nephrolithiasis include alkaline urine, hypercalciuria and hypocitraturia. In addition, we found hyperuricosuria in 21 per cent of the patients with type I renal tubular acidosis with nephrolithiasis. The most frequently occurring risk factor, hypocitraturia, is due to decreased filtered load and/or to increased tubular reabsorption of filtered citrate. While increased tubular reabsorption may be due to systemic acidosis, hypocitraturia occurs in incomplete renal tubular acidosis. Furthermore, alkali therapy (either bicarbonate or citrate salts) increases citrate excretion in complete and incomplete type I renal tubular acidosis. These data suggest that hypocitraturia in type I renal tubular acidosis may be due to a defect in proximal tubule function. Hypercalciuria appears to have 2 causes. It may be due to metabolic acidosis, usually in children with a hereditary defect in urine acidification. In other cases familial idiopathic hypercalciuria causes nephrocalcinosis and nephrolithiasis resulting in distal tubular damage and type I renal tubular acidosis. In these latter cases hypercalciuria is present in complete and incomplete type I renal tubular acidosis. Potassium citrate appears to reduce calcium excretion in both types of hypercalciuric type I renal tubular acidosis.
SPINAL CORD INJURY
Bladder stone incidence in persons with spinal cord injury: determinants and trends, 1973-1996. Chen Y, DeVivo MJ, Lloyd LK. Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham, Birmingham, Alabama, USA	Urology 2001 Nov;58(5):665-70 Abstract quote OBJECTIVES: To examine the current trend in the incidence of an initial bladder stone and the potential contributing factors among persons with spinal cord injury. METHODS: A longitudinal cohort of 1336 patients with spinal cord injury who were injured between 1973 and 1996 and followed up on a yearly basis up to 1999 in a single institution was used to estimate bladder stone incidence. Multivariable analysis was performed to identify risk factors for an initial bladder stone. RESULTS: During the study period, 229 incident bladder stone cases were documented. It is estimated that for those injured in 1973 to 1979, 1980 to 1984, 1985 to 1989, and 1990 to 1996, the 5-year cumulative incidence rate of an initial bladder stone was 29%, 23%, 14%, and 8%, respectively (P <0.0001). This decreasing trend was consistent for various demographic and clinical characteristics. During the first year after injury only, the bladder stone risk increased with decreasing age (P <0.0001) and was greater for whites. A neurologically complete lesion was associated with an increased bladder stone risk in later years (P = 0.008). Males and persons with indwelling and intermittent catheters had a higher risk during all the years after the injury. CONCLUSIONS: With improvement in urologic rehabilitation, bladder stone incidence has declined during the past several decades. The study results, however, suggest that new strategic interventions may be required to further prevent stone occurrence in individuals with spinal cord injury and a complete neurologic lesion who are using indwelling catheterization, because these patients are still at a relatively higher risk.
TRANSPLANTATION, KIDNEY
Urinary stones following renal transplantation. Kim H, Cheigh JS, Ham HW. Dept. of Int. Med., Div. of Nephrology, Sungkyunkwan Univ., School of Med., Kangbuk Samsung Hospital 108, Pyung-Dong, Jongro-Ku, Seoul 110-102, Korea.	Korean J Intern Med 2001 Jun;16(2):118-22 Abstract quote BACKGROUND: The formation of urinary tract stones following renal transplantation is a rare complication. The clinical features of stones after transplantation differ from those of non-transplant patients. Renal colic or pain is usually absent and rarely resembles acute rejection. METHODS: We retrospectively studied 849 consecutive kidney transplant patients in The Rogosin Institute/The Weill-Cornell Medical Center, New York who were transplanted between 1980 and 1997 and had functioning grafts for more than 3 months, to determine the incidence of stone formation, composition, risk factors and patient outcome. RESULTS: At our center, urinary stones were diagnosed in 15 patients (1.8%) of 849 functioning renal grafts for 3 or more months. Of the 15 patients, 10 were males and 5 were females in their third and fourth decade. Eight patients received their transplant from living donors and 7 from cadaveric donors. The stones were first diagnosed between 3 and 109 months after transplantation (mean 17.8 months) and 5 patients had recurrent episodes. The stones were located in the bladder in 11 cases (73.3%), transplanted kidney in 3 cases and in multiple sites in one case. The size of stones varied from 3.4 mm to 40 mm (mean 12 mm). The composition of stones was a mixed form of calcium oxalate and calcium phosphate in 5 cases and 4 patients had infected stones consisting of struvite or mixed form of struvite and calcium phosphate. Factors predisposing to stone formation included tertiary hyperparathyroidism (n = 8), hypercalciuria (n = 5), recurrent urinary tract infection (n = 5), hypocitraturia (n = 4), and obstructive uropathy (n = 2). Many cases had more than one risk factor. Clinically, painless hematuria was observed in 6 patients and dysuria without bacteriuria in 5 patients. None had renal colic or severe pain at any time. There were no changes in graft function at diagnosis and after removal of stones. Five patients passed stones spontaneously and 8 patients underwent cystoscopy for stone removal. CONCLUSION: Urinary stone formation following kidney transplantation is a rare complication (1.8%). Hyperparathyroidism, hypercalciuria, recurrent urinary tract infection and hypocitraturia are the most common risk factors, but often there are multiple factors which predispose to stone formation. To detect stones and determine their location and size, ultrasonography appears to be the most useful diagnostic tool. Prompt diagnosis, the removal of stones and stone-preventive measures can prevent adverse effects on renal graft outcome.

PATHOGENESIS	CHARACTERIZATION
CALCIUM STONES
Study of urinary calcium excretion after oral calcium load in stone formers, their spouses and first-degree blood relatives. Kaul P, Sidhu H, Vaidyanathan S, Thind SK, Nath R. Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, India.	Urol Int 1994;52(2):93-7 Abstract quote Hypercalciuria has long been considered a common abnormality in stone formers, and familial predisposition to renal stone formation has also been reported. Renal stone formers, their spouses and first-degree blood relatives (the latter two groups of subjects had no previous or present history of stone disease) were investigated for their response to an oral load of 2 g calcium (as di-calcium phosphate). Serum calcium, phosphorus, uric acid, creatinine and urea were within the normal range in all the subjects initially as well as 4 h after the load. After the oral calcium load, 66.6% of the stone formers, 25% of the first-degree relatives and none of the spouses were hypercalciuric. Administration of 2 g calcium produced a significantly greater urinary excretion of calcium in stone formers (123.8 +/- 43 mg/8 h, p < 0.001) and their first-degree blood relatives (89.8 +/- 26 mg/8 h, p < 0.01) as compared to the spouses of stone formers (65.5 +/- 12.8 mg/8 h). A significant increase in urinary calcium excretion after calcium loading was also found among the stone formers (p < 0.01) as compared to their first-degree blood relatives. A significantly higher mean rise in calcium excretion (over the basal excretion) in calcium stone formers (p < 0.001) and their first-degree blood relatives (p < 0.01), as compared to the spouses of stone formers suggests a greater predisposition to renal stone disease in first-degree blood relatives than the spouses of the stone patients
FIBRONECTIN
Comparison of fibronectin content in urinary macromolecules between normal subjects and recurrent stone formers. Tsujihata M, Miyake O, Yoshimura K, Kakimoto K, Takahara S, Okuyama A. Department of Urology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.	Eur Urol 2001 Oct;40(4):458-62 Abstract quote OBJECTIVES: Fibronectin (FN: 230 kD) is a multifunctional alpha(2)-glycoprotein distributed throughout the extracellular matrix and body fluids. Recent studies have shown that a variety of molecules, including FN, inhibit the endocytosis of calcium oxalate (CaOx) crystals in vitro. We recently reported that FN was oversecreted from the renal tubular cells as a result of the stimulation of CaOx crystals, and inhibited the aggregation of CaOx crystals and the adhesion of CaOx crystals to the renal tubular cells. In the present study, we investigated the difference of FN content in urinary macromolecules (UMMs) between normal subjects and recurrent stone formers. MATERIALS AND METHODS: Urinary parameters in relation to urolithiasis of normal subjects and recurrent stone formers were measured. Proteins in extracted UMMs from urine of normal subjects and recurrent stone formers were measured with a BioRad protein assay, GAGs in each UMMs with a modified DMB assay and the FN content with the ELISA method. RESULTS: In urinary parameters, citrate was significantly higher in urine from normal subjects (female) than normal subjects (male) or recurrent stone formers, and the other parameters showed no differences between each group. The protein concentrations in UMMs showed no differences between each group. Normal subjects (male and female) showed a significantly higher concentration of GAGs than recurrent stone formers (with and without silent stone). Compared with normal subjects and recurrent stone formers without silent stones, higher FN levels were found in recurrent stone formers with silent stones. Normal subjects showed a significantly higher concentration of FN than recurrent stone formers without silent stones. No difference in FN level was shown between normal subjects (male) and normal subjects (female). CONCLUSION: Recurrent stone formers with silent stones showed a significantly higher concentration of FN in UMMs than normal subjects. This finding suggests that FN might be oversecreted from the renal tubular cells as a result of the stimulation of CaOx stones in vivo. Recurrent stone formers without silent stones showed a significantly lower concentration of FN in UMMs than normal subjects. From this finding it is suggested that FN might play a role as a potent inhibitor of CaOx urolithiasis in a clinical setting.
INDINAVIR
Urinary Cytology Associated With Human Polyomavirus and Indinavir Therapy in HIV-Infected Patients Armando C. Filie, MD, Anna Maria Wilder, CT(ASCP), Keith Brosky, CT(ASCP), Jeffrey B. Kopp, MD, Kirk D. Miller, MD, and Andrea Abati, MD	Am J Clin Pathol 2002;117:922-926 Abstract quote We retrospectively analyzed 155 urine cytology samples (78 from patients treated with indinavir; 77, no indinavir) from 90 HIV+ patients to evaluate possible association between human polyomavirus and hematuria and to describe indinavir-associated urinary cytologic findings. The CD4 count also was recorded. Variables studied included the presence of cellular viral changes consistent with polyomavirus infection (PVCs), microscopic hematuria, multinucleated cells, indinavir crystals, neutrophils, and eosinophils. Twenty-two samples (15.8%) from patients with CD4 counts of more than 200/µL (>200 × 106/L) showed PVCs. Multinucleated cells, of presumed histiocytic origin based on morphologic features and selective immunocytochemical findings, were present in a higher percentage of samples from indinavir-treated patients. Neutrophils were present in a higher percentage of indinavir-treated patients. Indinavir crystals were identified in 9 samples (12%) from patients receiving indinavir. The lower percentage of PVCs in HIV+ patients with high CD4 counts likely represents an indirect antipolyomavirus indinavir effect by boosting immunity. Multinucleated cells (presumably histiocytic) and acute inflammation are associated with indinavir therapy. Indinavir crystals have a characteristic fan or circular lamellate appearance. Because indinavir crystals may be associated with genitourinary disease, recognizing and reporting them is clinically relevant in HIV+ patients.
NANOBACTERIA
URIC ACID STONES
Identification of a new candidate locus for uric acid nephrolithiasis. Ombra MN, Forabosco P, Casula S, Angius A, Maestrale G, Petretto E, Casu G, Colussi G, Usai E, Melis P, Pirastu M. Istituto di Genetica Molecolare, CNR, 07040 Santa Maria La Palma (SS), Italy.	Am J Hum Genet 2001 May;68(5):1119-29 Abstract quote Renal stone formation is a common multifactorial disorder, of unknown etiology, with an established genetic contribution. Lifetime risk for nephrolithiasis is approximately 10% in Western populations, and uric acid stones account for 5%-10% of all stones, depending on climatic, dietary, and ethnic differences. We studied a small, isolated founder population in Sardinia, characterized by an increased prevalence of uric acid stones, and performed a genomewide search in a deep-rooted pedigree comprising many members who formed uric acid renal stones. The pedigree was created by tracing common ancestors of affected individuals through a genealogical database based on archival records kept by the parish church since 1640. This genealogical information was used as the basis for the study strategy, involving screening for alleles shared among affected individuals, originating from common ancestors, and utilization of large pedigrees to obtain greater power for linkage detection. We performed multistep linkage and allele-sharing analyses. In the initial stage, 382 markers were typed in 14 closely related affected subjects; interesting regions were subsequently investigated in the whole sample. We identified two chromosomal regions that may harbor loci with susceptibility genes for uric acid stones. The strongest evidence was observed on 10q21-q22, where a LOD score of 3.07 was obtained for D10S1652 under an affected-only dominant model, and a LOD score of 3.90 was obtained using a dominant pseudomarker assignment. The localization was supported also by multipoint allele-sharing statistics and by haplotype analysis of familial cases and of unrelated affected subjects collected from the isolate. In the second region on 20q13.1-13.3, multipoint nonparametric scores yielded suggestive evidence in a approximately 20-cM region, and further analysis is needed to confirm and fine-map this putative locus. Replication studies are required to investigate the involvement of these regions in the genetic contribution to uric acid stone formation.

LABORATORY/RADIOLOGIC/ OTHER TESTS	CHARACTERIZATION
RADIOLOGIC
CT
Computed tomography versus intravenous urography in diagnosis of acute flank pain from urolithiasis: a randomized study comparing imaging costs and radiation dose. Thomson JM, Glocer J, Abbott C, Maling TM, Mark S. Department of Radiology, Christchurch Hospital, Christchurch, New Zealand.	Australas Radiol 2001 Aug;45(3):291-7 Abstract quote The equivalent sensitivity of non-contrast computed tomography (NCCT) and intravenous urography (IVU) in the diagnosis of suspected ureteric colic has been established. Approximately 50% of patients with suspected ureteric colic do not have a nephro-urological cause for pain. Because many such patients require further imaging studies, NCCT may obviate the need for these studies and, in so doing, be more cost effective and involve less overall radiation exposure. The present study compares the total imaging cost and radiation dose of NCCT versus IVU in the diagnosis of acute flank pain. Two hundred and twenty-four patients (157 men; mean age 45 years; age range 19-79 years) with suspected renal colic were randomized either to NCCT or IVU. The number of additional diagnostic imaging studies, cost (IVU A$136; CTU A$173), radiation exposure and imaging times were compared. Of 119 (53%) patients with renal obstruction, 105 had no nephro-urological causes of pain. For 21 (20%) of these patients an alternative diagnosis was made at the initial imaging, 10 of which were significant. Of 118 IVU patients, 28 (24%) required 32 additional imaging tests to reach a diagnosis, whereas seven of 106 (6%) NCCT patients required seven additional imaging studies. The average total diagnostic imaging cost for the NCCT group was A$181.94 and A$175.46 for the IVU group (P < 0.43). Mean radiation dose to diagnosis was 5.00 mSv (NCCT) versus 3.50 mSv (IVU) (P < 0.001). Mean imaging time was 30 min (NCCT) versus 75 min (IVU) (P < 0.001). Diagnostic imaging costs were remarkably similar. Although NCCT involves a higher radiation dose than IVU, its advantages of faster diagnosis, the avoidance of additional diagnostic imaging tests and its ability to diagnose other causes makes it the study of choice for acute flank pain at Christchurch Hospital.
Ultrasound vs CT for the detection of ureteric stones in patients with renal colic. Patlas M, Farkas A, Fisher D, Zaghal I, Hadas-Halpern I. Department of Radiology, Shaare Zedek Medical Center, Jerusalem 91031, Israel.	Br J Radiol 2001 Oct;74(886):901-4 Abstract quote The aim of our study was to compare the accuracy of non-contrast spiral CT with ultrasound (US) for the diagnosis of ureteral calculi in the evaluation of patients with acute flank pain. 62 consecutive patients with flank pain were examined with both CT and US over a period of 9 months. All patients were prospectively defined as either positive or negative for ureterolithiasis, based on follow-up evaluation. 43 of the 62 patients were confirmed as having ureteral calculi based on stone recovery or urological interventions. US showed 93% sensitivity and 95% specificity in the diagnosis of ureterolithiasis; CT showed 91% and 95%, respectively. Pathology unrelated to urinary stone disease was demonstrated in six patients. Although both modalities were excellent for detecting ureteral stones, consideration of cost and radiation lead us to suggest that US be employed first and CT be reserved for when US is unavailable or non-diagnostic.
CT urograms in pediatric patients with ureteral calculi: do adult criteria work? Smergel E, Greenberg SB, Crisci KL, Salwen JK. Department of Radiology, St. Christopher's Hospital for Children, Erie Avenue at Front Street, Philadelphia, PA 19134, USA.	Pediatr Radiol 2001 Oct;31(10):720-3 Abstract quote BACKGROUND: Secondary signs of urinary obstruction associated with ureteral calculi are useful adjuncts to diagnosis in adults with renal colic evaluated by unenhanced helical CT. OBJECTIVE: Our purpose was to evaluate the frequency of secondary signs of obstruction in children with renal colic undergoing unenhanced helical CT. MATERIALS AND METHODS: Ureteral calculi were identified in 20 of 61 children with acute flank pain examined by unenhanced helical CT. Each imaging study was evaluated for the presence of secondary signs of urinary obstruction. The frequencies of individual signs were compared with each other by means of the McNemar test. RESULTS: Six children had no secondary sign identified. In the remaining 14 children, proximal ureteral dilatation was seen in 10, renal enlargement in 10, hydronephrosis in 9, tissue rim sign in 6, decreased kidney attenuation in 5, and perinephric stranding in 1. Comparison of the frequencies strongly suggested that perinephric stranding occurs less frequently than proximal ureteral dilatation (P = 0.004), hydronephrosis (P = 0.008), or renal enlargement (P = 0.012). CONCLUSION: Perinephric stranding, a common secondary sign in adults with ureteral calculi, occurs less frequently in children than other reported secondary signs.
Value of multislice helical CT scans and maximum-intensity-projection images to improve detection of ureteral stones at abdominal radiography. Van Beers BE, Dechambre S, Hulcelle P, Materne R, Jamart J. Department of Radiology, Universite Catholique de Louvain, Saint-Luc University Hospital, Ave. Hippocrate 10, B-1200 Brussels, Belgium.	AJR Am J Roentgenol 2001 Nov;177(5):1117-21 Abstract quote OBJECTIVE: The purpose of this study was to assess the improvement in the detection of ureteral stones on abdominal radiographs when the stones were viewed on multislice helical CT scans and maximum-intensity-projection (MIP) images. SUBJECTS AND METHODS: The study included 72 patients with renal colic who underwent abdominal radiography and multislice helical CT. For each patient, a frontal MIP image was generated, and the stone, when present, was marked with a cross on the transverse CT scan. The cross appeared automatically on the corresponding MIP image. The CT examination was used as the standard of reference. The presence and location of ureteral stones on the abdominal radiographs were assessed during three interpretation sessions. In the first session, the abdominal radiographs were viewed alone. In the second, they were viewed with the transverse CT scans. In the third, the abdominal radiographs were viewed with the CT scans and the MIP images. RESULTS: Ureteral stones were present in 58 patients. The percentage of stones detected on the abdominal radiographs was 45% when the radiographs were viewed alone, 66% when they were viewed with the CT scans (p = 0.002 vs radiographs alone), and 78% when viewed with the CT scans and MIP images (p = 0.016 vs radiographs with CT scans). CONCLUSION: The sensitivity of stone detection on abdominal radiographs was greatest when the interpreters viewed the radiographs in conjunction with the CT scans and MIP images.
LABORATORY MARKERS
The preservation of urine samples for determination of renal stone risk factors. Nicar MJ, Hsu MC, Johnson T, Pak CY. Center on Mineral Metabolism and Clinical Research, Southwestern Medical School of the University of Texas Health Science Center at Dallas, TX 75235, USA.	Lab Med 1987 Jun;18(6):382-4 Abstract quote A preservation technique for urine specimens before determination of stone risk factors was evaluated. The purpose of these experiments was to prove the effectiveness of the preservatives used to prevent changes in the concentrations of those constituents measured. Measured concentrations in fresh specimens were compared with those in the same specimens after storage with the preservatives. Refrigeration at 4 degrees C up to five days was appropriate in a laboratory setting, as no significant changes in urinary concentrations occurred. Refrigeration, however, did not offer a convenient method for shipping. Chemical preservation was found to be an effective alternative to refrigeration. Thymol prevented changes in concentration of pH, citrate, uric acid, sulfate, sodium, potassium, and cyclic AMP, while a mixture of hydrochloric (HCl) acid and boric acid prevented changes in calcium, magnesium, phosphorus, oxalate, ammonium, and creatinine. Thus, the addition of thymol or HCl/boric acid to urine specimens will prevent significant changes in the concentrations of stone risk factors.
REPORTING
Integration of Text, Image, and Graphic Data From Different Sources in Laboratory Reports Example of Kidney Stone Reporting System Shang-Che Lin, MBA, MS Frederick Van Lente, PhD Adam Fadlalla, PhD Walter H. Henricks, MD	Am J Clin Pathol 2002;118:179-183 Abstract quote Laboratory analyses may generate multiple data types that may reside in disparate systems, and combining data into a report often requires laborious, error-prone methods. Kidney stone analysis, which includes biochemical composition analysis and gross feature documentation, is an example of such a situation. We developed the kidney stone reporting system (KISS) that integrates patient and specimen information from the laboratory information system, digital images of stones, and analytic instrument data into a concise report for the ordering clinicians. The database management environment facilitates archival and retrieval capabilities. Implementation of the system has reduced the number of manual steps necessary to produce a report and has saved approximately 30 technologist hours per week. Transcription errors have been virtually eliminated. The KISS represents an innovative use of standard tools to integrate text, image, and graphic data from disparate systems into an integrated laboratory report, without the need for expensive interfaces.

PROGNOSIS AND TREATMENT	CHARACTERIZATION
PROGNOSTIC FACTORS
TREATMENT
GENERAL
DISTAL STONES
Prospective randomized trial comparing shock wave lithotripsy and ureteroscopy for management of distal ureteral calculi. Pearle MS, Nadler R, Bercowsky E, Chen C, Dunn M, Figenshau RS, Hoenig DM, McDougall EM, Mutz J, Nakada SY, Shalhav AL, Sundaram C, Wolf JS Jr, Clayman RV. Department of Urology, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.	J Urol 2001 Oct;166(4):1255-60 Abstract quote PURPOSE: We compared the efficacy of shock wave lithotripsy and ureteroscopy for treatment of distal ureteral calculi. MATERIALS AND METHODS: A total of 64 patients with solitary, radiopaque distal ureteral calculi 15 mm. or less in largest diameter were randomized to treatment with shock wave lithotripsy (32) using an HM3 lithotriptor (Dornier MedTech, Kennesaw, Georgia) or ureteroscopy (32). Patient and stone characteristics, treatment parameters, clinical outcomes, patient satisfaction and cost were assessed for each group. RESULTS: The 2 groups were comparable in regard to patient age, sex, body mass index, stone size, degree of hydronephrosis and time to treatment. Procedural and operating room times were statistically significantly shorter for the shock wave lithotripsy compared to the ureteroscopy group (34 and 72 versus 65 and 97 minutes, respectively). In addition, 94% of patients who underwent shock wave lithotripsy versus 75% who underwent ureteroscopy were discharged home the day of procedure. At a mean followup of 21 and 24 days for shock wave lithotripsy and ureteroscopy, respectively, 91% of patients in each group had undergone imaging with a plain abdominal radiograph, and all studies showed resolution of the target stone. Minor complications occurred in 9% and 25% of the shock wave lithotripsy and ureteroscopy groups, respectively (p value was not significant). No ureteral perforation or stricture occurred in the ureteroscopy group. Postoperative flank pain and dysuria were more severe in the ureteroscopy than shock wave lithotripsy group, although the differences were not statistically significant. Patient satisfaction was high, including 94% for shock wave lithotripsy and 87% for ureteroscopy (p value not significant). Cost favored ureteroscopy by $1,255 if outpatient treatment for both modalities was assumed. CONCLUSIONS: Ureteroscopy and shock wave lithotripsy were associated with high success and low complication rates. However, shock wave lithotripsy required significantly less operating time, was more often performed on an outpatient basis, and showed a trend towards less flank pain and dysuria, fewer complications and quicker convalescence. Patient satisfaction was uniformly high in both groups. Although ureteroscopy and shock wave lithotripsy are highly effective for treatment of distal ureteral stones, we believe that HM3 shock wave lithotripsy, albeit slightly more costly, is preferable to manipulation with ureteroscopy since it is equally efficacious, more efficient and less morbid.
EXTRACORPOREAL SHOCK-WAVE LITHOTRIPSY
Extracorporeal shock-wave lithotripsy: a comparative study of electrohydraulic and electromagnetic units. Matin SF, Yost A, Streem SB. Urological Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA	J Urol 2001 Dec;166(6):2053-6 Abstract quote PURPOSE: We determined the results of shock wave lithotripsy with a newer electromagnetic lithotriptor and compared them with those in a contemporary series of cases managed by an electrohydraulic lithotriptor using identical treatment and followup criteria at a single center. MATERIALS AND METHODS: Between 1995 and 1999, 356 patients (375 renal units, 483 upper urinary tract stones) meeting study inclusion criteria were treated with an MFL 5000 electrohydraulic shock wave lithotripsy unit (Dornier Medical Systems, Inc., Marietta, Georgia). From 1999 to 2000, 173 patients (175 renal units; 218 upper urinary tract stones) meeting identical study inclusion criteria were treated using an electromagnetic Modulith SLX shock wave lithotripsy unit (Karl Storz Lithotripsy, Atlanta, Georgia). In each group stone-free results were determined by plain abdominal x-ray and renal ultrasound 1 month after lithotripsy and efficiency quotients were developed. Baseline patient and stone characteristics were compared by the Wilcoxon rank sum and Fisher exact tests. All variables significant at p <0.05 were included in subsequent outcome analysis using multivariate logistic regression. RESULTS: Baseline characteristics were equivalent, including patient age, gender, stone number and location, although patients treated with the electrohydraulic unit had a significantly larger median stone burden (103 versus 71 mm.2, p = 0.015). Multivariate regression analysis demonstrated a higher stone-free rate in the electrohydraulic group (77% versus 67%, p = 0.01) but also a higher rate of total adjunctive measures (56% versus 47%, p = 0.04). Consequently the efficiency quotients were comparable for the electrohydraulic and electromagnetic lithotripsy units (0.45 and 0.42, respectively, p = 0.43). CONCLUSIONS: Electrohydraulic lithotripsy resulted in a higher stone-free rate at 1 month, although it was associated with a higher rate of auxiliary measures. Ultimately the efficiency quotients were equivalent, implying that these 2 contemporary energy sources are acceptable. According to single center treatment and followup criteria they are equally efficacious.
LOWER POLE STONES
Mechanical percussion, inversion and diuresis for residual lower pole fragments after shock wave lithotripsy: a prospective, single blind, randomized controlled trial. Pace KT, Tariq N, Dyer SJ, Weir MJ, D'A Honey RJ. St. Michael's Hospital, University of Toronto, Ontario, Canada.	J Urol 2001 Dec;166(6):2065-71 Abstract quote PURPOSE: We compare the effectiveness of mechanical percussion and inversion with observation for eliminating lower caliceal fragments 3 months after shock wave lithotripsy. MATERIALS AND METHODS: At 3 months after shock wave lithotripsy 69 patients with residual lower caliceal fragments 4 mm. or less were randomized to receive either mechanical percussion and inversion or observation for 1 month. The observation group then received crossover mechanical percussion and inversion if fragments persisted. All patients were followed with plain film of the kidneys, ureters and bladder to assess the stone area and stone-free status, and renal tomography or noncontrast spiral computerized tomography to confirm stone-free status. A blinded radiologist reviewed all films. Patients were treated with a mechanical chest percussor applied to the flank while inverted to greater than 60 degrees after receiving 20 mg. furosemide. RESULTS: A total of 35 patients were randomized to receive immediate mechanical percussion and inversion therapy and 34 observation. Of the patients in the observation group 28 subsequently received mechanical percussion and inversion after completing the observation period. The groups were not different in gender, body mass index, side affected, stone location or renal anatomical features. The mechanical percussion and inversion group had a substantially higher stone-free rate than the observation group (40% versus 3%, respectively, p <0.001). The mechanical percussion and inversion group also had a greater improvement in total stone area than controls (-63.3% versus +2.7%, respectively, p <0.001). No significant adverse effects were noted in the mechanical percussion and inversion group. CONCLUSIONS: Mechanical percussion and inversion is a safe and effective treatment option for residual lower caliceal fragments 3 months after shock wave lithotripsy. Nearly 50% of patients become stone-free, and stone burden is decreased by 50% in the remainder.
Lower pole I: a prospective randomized trial of extracorporeal shock wave lithotripsy and percutaneous nephrostolithotomy for lower pole nephrolithiasis-initial results. Albala DM, Assimos DG, Clayman RV, Denstedt JD, Grasso M, Gutierrez-Aceves J, Kahn RI, Leveillee RJ, Lingeman JE, Macaluso JN Jr, Munch LC, Nakada SY, Newman RC, Pearle MS, Preminger GM, Teichman J, Woods JR.	J Urol 2001 Dec;166(6):2072-80 Abstract quote PURPOSE: The efficacy of shock wave lithotripsy and percutaneous stone removal for the treatment of symptomatic lower pole renal calculi was determined. MATERIALS AND METHODS: A prospective randomized, multicenter clinical trial was performed comparing shock wave lithotripsy and percutaneous stone removal for symptomatic lower pole only renal calculi 30 mm. or less. RESULTS: Of 128 patients enrolled in the study 60 with a mean stone size of 14.43 mm. were randomized to percutaneous stone removal (58 treated, 2 awaiting treatment) and 68 with a mean stone size of 14.03 mm. were randomized to shock wave lithotripsy (64 treated, 4 awaiting treatment). Followup at 3 months was available for 88% of treated patients. The 3-month postoperative stone-free rates overall were 95% for percutaneous removal versus 37% lithotripsy (p <0.001). Shock wave lithotripsy results varied inversely with stone burden while percutaneous stone-free rates were independent of stone burden. Stone clearance from the lower pole following shock wave lithotripsy was particularly problematic for calculi greater than 10 mm. in diameter with only 7 of 33 (21%) patients becoming stone-free. Re-treatment was necessary in 10 (16%) lithotripsy and 5 (9%) percutaneous cases. There were 9 treatment failures in the lithotripsy group and none in the percutaneous group. Ancillary treatment was necessary in 13% of lithotripsy and 2% percutaneous cases. Morbidity was low overall and did not differ significantly between the groups (percutaneous stone removal 22%, shock wave lithotripsy 11%, p =0.087). In the shock wave lithotripsy group there was no difference in lower pole anatomical measurements between kidneys in which complete stone clearance did or did not occur. CONCLUSIONS: Stone clearance from the lower pole following shock wave lithotripsy is poor, especially for stones greater than 10 mm. in diameter. Calculi greater than 10 mm. in diameter are better managed initially with percutaneous removal due to its high degree of efficacy and acceptably low morbidity.
PERCUTANEOUS NEPHROLITHOTOMY
Prospective randomized study of various techniques of percutaneous nephrolithotomy. Feng MI, Tamaddon K, Mikhail A, Kaptein JS, Bellman GC. Department of Urology, Kaiser Permanente Medical Center, Los Angeles, California 900247, USA	Urology 2001 Sep;58(3):345-50 Abstract quote OBJECTIVES: To compare the modifications of the technique of percutaneous nephrolithotomy (PCN), including "mini-PCN" and tubeless PCN, to establish which technique is associated with the least morbidity and complications. METHODS: We performed a prospective randomized trial to assess the efficacy and morbidity of each method of percutaneous renal access. Standard PCN involved tract dilation to 30F for passage of a 34F working sheath, and our "mini-PCN" involved tract dilation to 22F for passage of a 26F sheath. Tubeless PCN involved the use of a double-J stent for internal drainage without the use of a nephrostomy tube for external drainage at termination of the procedure. Thirty patients (10 patients in each group) were enrolled, and 27 patients completed the study. All three groups were compared with regard to postoperative pain using a validated pain questionnaire comprised of a visual analogue scale and a verbal rating scale. The operative time, estimated blood loss, stone burden, procedure success rate, stone-free rate, length of hospitalization, total procedural cost, and complications were also compared for each technique. RESULTS: The tubeless PCN population required less morphine use, had a decreased length of hospitalization, and had a smaller total procedural cost compared with the other two groups. One complication was noted in both the standard and mini-PCN groups, consisting of renal bleeding requiring a 2 and 3-U blood transfusion in the standard and mini-PCN groups, respectively. CONCLUSIONS: The tubeless technique is associated with the least amount of morbidity and the greatest cost efficiency compared with the other techniques. No overall advantage was found for the mini-PCN versus the standard technique, but the mini-PCN is at a slight disadvantage because of poorer visualization and optics and difficulty with use of the nephroscopic graspers.

Chemical Composition of Stones	Percentage %
Calcium oxalate/Calcium phosphate	75
Magnesium ammonium phosphate	10-15
Uric acid	6
Mixed magnesium, calcium, uric acid	3-10%
Cystine	1-2%
Xanthine	Rare
Adenine	Rare

EPIDEMIOLOGY	CHARACTERIZATION
GEOGRAPHY
KOREANS
Prevalence and risk factors of urinary stones in Koreans. Kim SC, Moon YT, Hong YP, Hwang TK, Choi SH, Kim KJ, Sul CK, Park TC, Kim YG, Park KS. Department of Urology, College of Medicine, Chung-Ang University, Seoul, Korea.	J Korean Med Sci 1998 Apr;13(2):138-46 Abstract quote To estimate the prevalence of urinary stone disease in Koreans, and to determine the inter-relationships between urinary stone disease and various epidemiological factors, 1,521 controls and 1,177 cases with urinary stones were evaluated. Of special interest in this study were: 1) proportion of past urinary stone history among controls; 1.9% 2) the point prevalence rate of urinary stones among controls; 0.2% 3) the recurrence rate of urinary stones (the proportion of past history of urinary stone) among cases; 56.8% 4) high incidences (76.3%) in the thirties to the fifties among cases 5) the risk factors for urolithogenesis; obesity [higher than 25 of BMI (body mass index, weight/height2)], more than 10 year-experience as a production worker, past stone history, familial stone history, low physical activity (< 2,000 Kcal/day), and low intake of fruit. However, the well-known risk factors for urinary stones; over intake of meat or fish and milk or dairy products, perspiration, amount and kind of drinking water, and stress unexpectedly were not significantly different between the controls and the cases.

GROSS APPEARANCE/ CLINICAL VARIANTS	CHARACTERIZATION
GENERAL
VARIANTS
FAMILIAL
Idiopathic hypercalciuria and hyperuricosuria: family prevalence of nephrolithiasis. Polito C, La Manna A, Nappi B, Villani J, Di Toro R. Clinica Pediatrica III, Naples, Italy.	Pediatr Nephrol 2000 Oct;14(12):1102-4 Abstract quote We studied the prevalence of a history of nephrolithiasis in first- and second-degree relatives of 74 children with hypercalciuria (HC), 61 with hyperuricosuria (HU), and 41 with HC plus HU, and in a control population of 261 children with different diseases. Family history of nephrolithiasis was found in 69% of HC, 75% of HU, 78% of HC plus HU, and 22% of control patients. The prevalence was not different among HC, HU, and HC plus HU groups, but was significantly higher in each study group than the control group (P=0.0001). Body mass index >95th percentile was found in only 4.7% of the patients with HC or HC plus HU. Calculi (>3 mm in diameter) were present in 8.9% of the patients with a family history of nephrolithiasis and in 9.4% of those with no family history (P=0.85). Microcalculi (<3 mm in diameter) were found by sonography in 56.6% of the patients with and in 53.3% of those without a family history of nephrolithiasis (P=0.83). Children with HC and/or HU have a strong familial prevalence of nephrolithiasis. Obesity does not seem to affect the association of familial nephrolithiasis and hypercalciuria in children. The presence of nephrolithiasis in families of children with HC and/or HU is not associated with a higher rate of formation of calculi or microcalculi.