The thyroid panel is often referred to as thyroid function tests. The
usual panel includes the following tests:
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CHARACTERIZATION |
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Strategies for thyrotropin use to monitor patients with treated
thyroid carcinoma.
Ladenson PW.
Division of Endocrinology and Metabolism, The Johns Hopkins University
School of Medicine, Baltimore, Maryland, USA.
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Thyroid 1999 May;9(5):429-33 Abstract quote
Detection of residual and recurrent thyroid carcinoma requires long-term
monitoring of patients with serum thyroglobulin measurement and radioiodine
scanning during temporary thyrotropin (TSH) stimulation.
Recombinant thyrotropin (rTSH) permits these studies to be performed
without the morbidity associated with withdrawal of thyroid hormone
therapy. A protocol for rTSH use is proposed, beginning with measurement
of serum thyroglobulin during TSH suppression. Patients at significant
risk of recurrence with a low initial thyroglobulin level then have
rTSH stimulation testing. Patients with positive rTSH-stimulated thyroglobulin
concentrations and/or radioiodine scans can then be directed for appropriate
therapy. The previously studied 2-dose rTSH protocol with imaging at
48 hours after 131I dosing requires Monday-through-Friday testing in
most settings, but new regimens may be established. rTSH-stimulated
testing may be less accurate in patients with thyroglobulin autoantibodies
and those with residual normal thyroid tissue, and is generally unnecessary
when there is other evidence of residual disease.
Physicians should consider patients' pretest probability of disease
in deciding whether and how often to perform rTSH-stimulated testing
after primary treatment for thyroid carcinoma.
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Clinical experience with recombinant human thyroid-stimulating hormone
(rhTSH): serum thyroglobulin measurement.
Pacini F, Lippi F.
Department of Endocrinology and Metabolism, Universita degli Studi
di Pisa, Italy.
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J Endocrinol Invest 1999;22(11 Suppl):25-9 Abstract quote
Only normal or neoplastic thyroid follicular cells produce and secrete
the prohormone, thyroglobulin (Tg). For some 25 years, elevated serum
concentrations of Tg therefore have been employed as a post-operative
marker for well-differentiated thyroid carcinoma.
The aim of serum Tg measurement is to identify patients requiring:
A) further testing to confirm the presence and to determine the stage,
site and functionality of tumour; and/or B) further treatment. Serum
Tg testing has the advantages of superior sensitivity to radioiodine
whole-body scanning (WBS), lack of false positive readings, simplicity,
speed, low cost, precision and wide availability. However, major limitations
of serum Tg testing are interference by serum anti-Tg antibodies and
decreased sensitivity during THST. To obviate this last drawback, the
use of recombinant human thyroid-stimulating hormone (rhTSH) has been
clinically investigated as a preparative adjunct to serum Tg testing
in the diagnostic follow-up of well-differentiated thyroid cancer.
A large, multicentre international Phase III study now has confirmed
evidence from earlier Phase I/II and Phase III trials and established
the safety and efficacy of rhTSH in stimulating Tg release by residual
and neoplastic thyroid tissue. This confirmatory study has clearly shown
that 1) rhTSH administration significantly increases sensitivity of
serum Tg measurement in patients on THST; and 2) by permitting sensitive
diagnostic follow-up with serum Tg measurement and/or radioiodine WBS
during THST, rhTSH administration improves patient comfort and quality
of life compared to THST withdrawal. Thus use of the drug in diagnostic
follow-up recently has received regulatory approval in the United States,
and such approval is pending in the European Union. With regulatory
approval, rhTSH is likely to gain an important role as a preparative
adjunct to serum Tg testing in everyday practice.
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Diagnosis of thyroid disease in hospitalized patients: a systematic
review.
Attia J, Margetts P, Guyatt G.
Department of Internal Medicine, McMaster University, Hamilton,
Ontario, Canada.
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Arch Intern Med 1999 Apr 12;159(7):658-65 Abstract quote
BACKGROUND: The optimal approach for the diagnosis of hypothyroidism
and hyperthyroidism in hospitalized patients is controversial.
OBJECTIVES: To estimate the prevalence of undiagnosed thyroid disease
among inpatients, review the usefulness of clinical signs and symptoms,
and elucidate the characteristics of the sensitive thyrotropin (thyroid-stimulating
hormone) (sTSH) test in this population.
METHODS: We undertook a systematic review of the literature by conducting
a MEDLINE search covering January 1966 through December 1996. Searching
was conducted in duplicate and independently. Specific inclusion and
exclusion criteria were predetermined.
RESULTS: Prevalence of thyroid disease among inpatients is approximately
1% to 2% and is similar to the outpatient population. Absence of clinical
features of thyroid disease lowers the pretest likelihood and makes
screening even less useful. Presence of clinical features, especially
those specific for thyroid disease (eg, goiter), may increase the pretest
likelihood and increase the yield of testing. Acute illness reduces
the specificity of second-generation sTSH tests for thyroid disease.
The positive likelihood ratio associated with an abnormal sTSH test
result in ill inpatients is about 10 compared with about 100 in outpatients.
CONCLUSION: In unselected general medical, geriatric, or psychiatric
inpatient populations, sTSH testing provides a low yield of true-positive
and many false-positive results.
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American Thyroid Association guidelines for detection of thyroid
dysfunction.
Ladenson PW, Singer PA, Ain KB, Bagchi N, Bigos ST, Levy EG, Smith
SA, Daniels GH, Cohen HD.
The Johns Hopkins University School of Medicine, Baltimore, MD 21287-0003,
USA.
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Arch Intern Med 2000 Jun 12;160(11):1573-5 Abstract quote
OBJECTIVE: To define the optimal approach to identify patients with
thyroid dysfunction.
PARTICIPANTS: The 8-member Standards of Care Committee of the American
Thyroid Association prepared a draft, which was reviewed by the association's
780 members, 50 of whom responded with suggested revisions.
EVIDENCE: Relevant published studies were identified through MEDLINE
and the association membership's personal resources.
CONSENSUS PROCESS: Consensus was reached at group meetings. The first
draft was prepared by a single author (P.W.L.) after group discussion.
Suggested revisions were incorporated after consideration by the committee.
CONCLUSIONS: The American Thyroid Association recommends that adults
be screened for thyroid dysfunction by measurement of the serum thyrotropin
concentration, beginning at age 35 years and every 5 years thereafter.
The indication for screening is particularly compelling in women, but
it can also be justified in men as a relatively cost-effective measure
in the context of the periodic health examination. Individuals with
symptoms and signs potentially attributable to thyroid dysfunction and
those with risk factors for its development may require more frequent
serum thyrotropin testing.
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Practical application of recombinant thyrotropin testing in clinical
practice.
Ladenson PW, Ewertz ME, Dickey RA.
Division of Endocrinology and Metabolism, Department of Medicine,
The Johns Hopkins University School of Medicine, Baltimore, Maryland
21287-0003, USA
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Endocr Pract 2001 May-Jun;7(3):195-201 Abstract quote
OBJECTIVE: To review the indications for use of recombinant thyrotropin
(rTSH) and outline the details of implementation of rTSH diagnostic
testing in patients with treated thyroid cancer.
METHODS: We discuss the results of published clinical trials that have
compared rTSH-stimulated testing with conventional withdrawal of thyroid
hormone suppressive therapy. Appropriate candidates for rTSH testing
are described, and the typical schedule for rTSH testing and follow-up
is presented. An overview of coding and documentation for reimbursement
is also provided.
RESULTS: Clinical studies have found no significant difference in the
combined sensitivity of (131)I scans and serum thyroglobulin measurements
for detection of recurrent thyroid cancer after rTSH stimulation versus
withdrawal of thyroid hormone therapy. As expected, patients have fewer
symptoms and a more favorable mood state after use of rTSH. Patients
with thyroid cancer who have undergone total or near-total thyroidectomy
followed by 131I ablation can be considered for rTSH testing. For low-risk
patients, two cycles of rTSH testing 1 to 2 years apart, followed by
testing every 3 to 5 years, are recommended. For moderate- to high-risk
patients who have undergone one cycle of negative levothyroxine-withdrawal
testing, two cycles of rTSH testing at a 6- to 12-month interval, followed
by testing every 1 to 3 years for at least the first decade of follow-up,
are recommended. Most commercial insurance, Medicare, and Medicaid carriers
now cover rTSH, either in a prescription drug plan or under major medical
benefits.
CONCLUSION: Radioiodine scanning and serum thyroglobulin measurement
after intramuscular injection of rTSH are valuable new monitoring options
in patients with treated thyroid cancer, avoiding the adverse effects
of hypothyroidism.
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Thyroxine treatment in patients with symptoms of hypothyroidism
but thyroid function tests within the reference range: randomised double
blind placebo controlled crossover trial.
Pollock MA, Sturrock A, Marshall K, Davidson KM, Kelly CJ, McMahon
AD, McLaren EH.
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BMJ 2001 Oct 20;323(7318):891-5 Abstract quote
Objectives: To determine whether thyroxine treatment is effective in
patients with symptoms of hypothyroidism but with thyroid function tests
within the reference range, and to investigate the effect of thyroxine
treatment on psychological and physical wellbeing in healthy participants.
Design: Randomised double blind placebo controlled crossover trial.
Setting: Outpatient clinic in a general hospital. Participants: 25
patients with symptoms of hypothyroidism who had thyroid function tests
within the reference range, and 19 controls.
Methods: Participants were given thyroxine 100 &mgr;g or placebo to
take once a day for 12 weeks. Washout period was six weeks. They were
then given the other to take once a day for 12 weeks. All participants
were assessed physiologically and psychologically at baseline and on
completion of each phase.
Main outcome measures: Thyroid function tests, measures of cognitive
function and of psychological and physical wellbeing. Results: 22 patients
and 19 healthy controls completed the study. At baseline, patients'
scores on 9 out of 15 psychological measures were impaired when compared
with controls. Patients showed a significantly greater response to placebo
than controls in 3 out of 15 psychological measures. Healthy participants
had significantly lower scores for vitality when taking thyroxine compared
to placebo (mean (SD) 60 (17) v 73 (16), P<0.01). However, patients'
scores from psychological tests when taking thyroxine were no different
from those when taking placebo except for a poorer performance on one
visual reproduction test when taking thyroxine. Serum concentrations
of free thyroxine increased and those of thyroid stimulating hormone
decreased in patients and controls while they were taking thyroxine,
confirming compliance with treatment. Although serum concentrations
of free triiodothyronine increased in patients and controls taking thyroxine,
the difference between the response to placebo and to thyroxine was
significant only in the controls.
Conclusions: Thyroxine was no more effective than placebo in improving
cognitive function and psychological wellbeing in patients with symptoms
of hypothyroidism but thyroid function tests within the reference range.
Thyroxine did not improve cognitive function and psychological wellbeing
in healthy participants.
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Serum thyroglobulin concentrations and (131)i whole-body scan results
in patients with differentiated thyroid carcinoma after administration
of recombinant human thyroid-stimulating hormone.
David A, Blotta A, Bondanelli M, Rossi R, Roti E, Braverman LE,
Busutti L, Uberti EC.
Section of Endocrinology, Department of Biomedical Sciences and
Advanced Therapies, University of Ferrara, Ferrara.
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J Nucl Med 2001 Oct;42(10):1470-5 Abstract quote
The use of recombinant human thyroid-stimulating hormone (rhTSH) has
recently become available as an alternative diagnostic tool to assess
the persistence and recurrence of differentiated thyroid carcinoma (DTC)
in patients on thyroid hormone-suppressive therapy (THST) after near-total
or total thyroidectomy and ablative doses of (131)I. We report the results
of rhTSH administration in patients who were monitored for DTC.
METHODS: Thirty-three adult DTC patients (13 men, 20 women; mean age
+/- SE, 45.6 +/- 2.31 y; age range, 21-65 y) underwent diagnostic follow-up
after rhTSH administration at a dose of 0.9 mg once a day for 2 d. Whole-body
scanning and serum thyroglobulin (Tg) measurement were performed after
rhTSH administration. Patients were divided into 2 groups depending
on serum Tg concentrations on THST: 29 patients had Tg concentrations
of <2 ng/mL (group A) and 4 patients had Tg values of >2 ng/mL (group
B).
RESULTS: In group A, Tg values remained at <2 ng/mL in 25 patients
and increased from 1.1 +/- 0.14 ng/mL to 22.0 +/- 5.75 ng/mL (mean +/-
SE) in 4 patients after rhTSH administration. Whole-body scanning did
not reveal any uptake of (131)I in the 25 patients without an increase
in Tg, whereas (131)I uptake was evident in 2 of the 4 patients with
a rise in Tg. In group B, Tg values increased in all 4 patients from
17.3 +/- 6.35 ng/mL to 55.3 +/- 12.75 ng/mL, and (131)I uptake was evident
in 3 of the 4 patients. No major adverse effects were reported after
rhTSH administration.
CONCLUSION: Our results show that the measurement of serum Tg concentrations
after rhTSH has a higher diagnostic value than whole-body scanning in
detecting the persistence of thyroid tissue. Therefore, rhTSH should
be administered in TSH-suppressed patients with basal serum Tg concentrations
of <2 ng/mL because the increment in serum Tg concentrations may reveal
the persistence of thyroid tissue in these patients.
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