PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Thyroid Function Tests”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources
PubMed2003

Biologic variation is important for interpretation of thyroid function tests.

Large variations exist in thyrotropin (TSH) and thyroid hormones in serum. The components of variation include preanalytical, analytical, and biologic variation. This is divided into between- and within-individual variation. The latter consists of circadian and seasonal differences although there are indicators of a genetically determined starting point. The ratio of within- to between-individual variation describes the reliability of population-based reference ranges. This ratio is low for serum TSH, thyroxine (T(4)) and triiodothyronine (T(3)) indicating that laboratory reference ranges are relatively insensitive to aberrations from normality in the individual. Solutions are considered but reducing the analytical variation below the calculated analytical goals of 7%, 5% and 12% for serum T(3), T(4), and TSH does not improve diagnostic performance. Neither does determination of the individual set-point and reference range. In practice this means that population-based reference ranges are necessary but that it is important to recognize their limitations for use in individuals. Serum TSH responds with amplification to minor alterations in T(4) and T(3). A consistently abnormal TSH probably indicates that T(4) and T(3) are not normal for the individual even when inside the laboratory reference range. This underlines the importance of TSH in diagnosis and monitoring of thyroid dysfunctions. Also, it implies that subclinical thyroid disease may be defined in purely biochemical terms. Under critical circumstances such as pregnancy where normal thyroid function is of importance for fetal brain development, subclinical thyroid disease should be treated. Even TSH within the reference range may be associated with slightly abnormal thyroid function of the individual. The clinical importance of such small abnormalities in thyroid function in small children and pregnant women for brain development remains to be elucidated.

Circadian Rhythm↗
PubMed1987

Economy and efficiency in routine thyroid-function testing: use of a sensitive immunoradiometric assay for thyrotropin in a general hospital laboratory.

We measured thyrotropin (TSH) with a sensitive immunoradiometric assay (IRMA) in 2329 consecutive serum samples received for thyroid-function tests from hospital and general practice. Of these, 185 (7.9%) had TSH values less than 0.2 milli-int. unit/L: 33 (1.4%) were hyperthyroid, 20 (0.9%) were being treated for hyperthyroidism, 115 (4.9%) were receiving L-thyroxin, and 17 (0.7%) were clinically euthyroid but had severe non-thyroidal illnesses. In the first 506 serum samples, we also measured free thyroxin, free triiodothyronine (FT3), and total thyroxin. Thyroliberin (thyrotropin-releasing hormone, TRH) tests performed on 84 patients showed that an undetectable initial TSH (usually ascribable to therapy with thyroxin) predicted a flat TRH response. All untreated thyrotoxic patients had undetectable TSH. Experience confirmed that this TSH assay, in conjunction with a supplementary assay of FT3 when the TSH concentration is less than twice the limit of detection, is efficient and economical for routine evaluation of thyroid function in an unselected population.

Adult↗
PubMed1996

Disturbances of thyroid function tests by drugs.

Commonly prescribed drugs can variously cause changes in measuring serum T3 and T4 concentrations. Thus spuriously normal thyroid hormone levels may result in moderate hypo- or hyperthyroidism, or the influence of pharmacological substances may lead to a false diagnosis of thyroid disease in euthyroid subjects. On the other hand numerous pharmacological agents, especially those interacting with neurotransmitters, may influence TSH secretion, too. While generally such drug-induced abnormal thyroid tests do not correspond to clinical features of thyroid dysfunction, iodine containing drugs, especially amiodarone, may result in overt thyroid disease.

Amiodarone↗
PubMed2001

Thyroid function testing in eastern Nepal and the impact of CME on subsequent requests.

This study reveals 1 year's experience of the introduction of thyroid function tests (TFT) in B P Koirala Institute of Health Sciences (BPKIHS), a Medical University situated in eastern Nepal. These were performed on theadvice of doctors working in this region. The rational TFT advice by the medical practitioners was evaluated according to how closely the advice was in line with the algorithms recommended in the textbooks. Only about 14% of the TFT advice followed some rational strategy. A retrospective analysis showed that rational TFT advice could have reduced the cost of a TFT investigation to 43.11% without altering the patient management and disease outcome. Continuing medical education (CME) lectures arranged for a limited number of doctors were found to improve the quality of the subsequentTFT advising pattern. This emphasizes the importance of CME while introducing a costly laboratory test panel (e.g.TFT, lipid profile) needing a strategic approach.

Education, Medical, Continuing↗
PubMed2001

[Prescription of thyroid function tests in adults as a function of clinical circumstances and of patient management].

A group of experts composed of clinicians and biologists in 7 University Hospitals in the Aquitaine and Paris regions working within the framework of the Coordination Committee for Clinical Evaluation and Quality in Aquitaine (CCECQA) have developed prescription guidelines for thyroid function tests to be performed in adults. The goal was to determine strategies for prescribing thyroid hormones (T3 and T4) and thyroid stimulating hormone (TSH) to screen for thyroid function disorders and follow thyroid function. The resulting recommendations were based on a review of the literature and a consensus among the experts. The first part of the guidelines concern recommended prescriptions in different clinical situations (early diagnosis of hypothyroidism, early diagnosis of hyperthyroidism, follow-up of anti-thyroid drug treatments, follow-up of levothyroxin replacement therapy, institution and follow-up of treatments susceptible of inducing dysthyroidism, pregnancy and post-partum dysthyroidism, palpation of a thyroid nodule). The second part of the guidelines are devoted to prescriptions according to the therapeutic setting (emergency care, psychiatric care, geriatric care).

Adult↗
PubMed1995

Relationship of admission thyroid function tests to outcome in critical illness.

One hundred and eighty patients had serum thyrotropin, total triiodothyronine and free thyroxine concentrations measured within 3 h of admission to the Intensive Therapy Unit to assess whether thyroid function tests could predict outcome in critical illness. Overall mortality was 30.6%. Nonsurvivors were older (p = 0.001), and had higher APACHE II scores (p < 0.001) and predicted mortalities (p < 0.001). There was no difference in the median values of thyrotropin, total triiodothyronine and free thyroxine concentrations between survivors and nonsurvivors. Thyrotropin concentration was subnormal in 15 patients, normal in 152 and elevated in 13 patients. In contrast, 80 patients had subnormal triiodothyronine concentration. Free thyroxine was subnormal in five patients. Thyrotropin, total triiodothyronine and free thyroxine concentrations were not related to outcome (p = 0.360, p = 0.622, p = 0.726, respectively). No variable independently predicted death. Total triiodothyronine concentrations were lower in patients who received dopamine before admission to the intensive therapy unit than those who did not (p = 0.008); thyrotropin and free thyroxine concentrations were not influenced by dopamine administration. Serum concentrations of thyrotropin, total triiodothyronine and free thyroxine measured within 3 h of admission to the intensive therapy unit are not predictive of outcome.

Adolescent↗
PubMed1995

Thyroid function test changes with adjuvant tamoxifen therapy in postmenopausal women with breast cancer.

PURPOSE: While tamoxifen has been shown to alter concentration of many hormones and their binding globulins, there have been conflicting results regarding its effects on thyroid function tests. We sought to clarify these effects by studying subjects in a controlled clinical trial. PATIENTS AND METHODS: We evaluated a subset of postmenopausal women who had participated in a longitudinal, double-blind, randomized, placebo-controlled toxicity study of tamoxifen 10 mg orally, twice daily. There were 14 subjects in both the tamoxifen and placebo groups. Measurement of thyroid-binding globulin (TBG), thyroxine uptake (T-Uptake), thyroxine (T4), and thyroid-stimulating hormone (TSH), and an indirect estimate of the free T4 index (FTI), were made for each subject before and after 3 months of treatment. RESULTS: For T-Uptake, T4, and TBG, there were significant increases in the mean change from baseline to 3 months in the tamoxifen group compared with the placebo group (P = .02, .0001, and .003, respectively), while there were no significant changes in the measured TSH and in the calculated FTI. CONCLUSION: We conclude that tamoxifen therapy in postmenopausal women results in increased TBG, with secondary increases in measured T-Uptake and T4 following. However, TSH and FTI levels are unchanged, and treated women remain eumetabolic.

Breast Neoplasms↗
PubMed1988

Effects of widespread dermatitis and topical steroid therapy on thyroid function tests.

Five patients with extensive dermatitis and 5 normal subjects were treated with topical betamethasone valerate 0.1% (Betnovate, Glaxo) 19-34 g daily for 4 days. Thyroid functions tests were not affected by the treatment but some patients with widespread inflamed skin demonstrated altered serum thyroid hormone levels as a result of the euthyroid sick syndrome.

Administration, Cutaneous↗
PubMed1999

Changes in thyroid function tests during short-term salsalate use.

Although long-term administration of salsalate depresses blood levels of both total thyroxine (T4) and total triiodothyronine (T3) and at least transiently decreases serum thyrotropin (TSH), changes in thyroid function tests have not been fully characterized during its short-term use. It is also unclear if the observed changes are solely the result of decreased hormone binding to carrier proteins or if reduced hepatic 5'-monodeiodinase activity is important. Blood was sampled at baseline (day 0) and after 24 hours (day 1) and 72 hours (day 3) in eight subjects taking a therapeutic dose of salsalate 1,500 mg twice daily. Total T4 decreased from 90.1+/-7.7 nmol/L (mean+/-SD) on day 0 to 82.9+/-8.6 nmol/L on day 1 (P=.1 v baseline) and 68.6+/-8.7 nmol/L on day 3 (P=.0001). Total T3 decreased from 1.76+/-0.20 nmol/L to 1.61+/-0.16 nmol/L on day 1 (P<.05) and 1.31+/-0.27 nmol/L on day 3 (P=.002). The T4/T3 ratio was 51.7+/-7.7 at baseline and remained unchanged after 3 days. Levels of reverse T3 (rT3) were reduced from 0.24+/-0.05 nmol/L to 0.18+/-0.02 nmol/L on day 3 (P<.05). While the free T4 index (FTI) declined in parallel with total T4, the free T4 level by direct equilibrium dialysis (FTD) was unchanged after 3 days. Serum TSH decreased from 1.47+/-0.47 mU/L to 0.91+/-0.27 mU/L after 1 day (P<.05) and remained suppressed after 3 days (0.95+/-0.49 mU/L, P<.05). In conclusion, (1) therapeutic doses of salsalate significantly decrease serum concentrations of total T4, total T3, and rT3 to about 75% of baseline levels after 3 days without altering the T4/T3 ratio; (2) although the FTD does not change, serum TSH concentrations remain suppressed; and (3) the proportionate decrease in total thyroid hormone levels suggests that inhibition of hormone binding to serum proteins is more important in producing these changes than reduced hepatic 5'-monodeiodinase activity.

Adult↗
PubMed2005

Clinical investigation: thyroid function test abnormalities in cardiac arrest associated with acute coronary syndrome.

INTRODUCTION: It is known that thyroid homeostasis is altered during the acute phase of cardiac arrest. However, it is not clear under what conditions, how and for how long these alterations occur. In the present study we examined thyroid function tests (TFTs) in the acute phase of cardiac arrest caused by acute coronary syndrome (ACS) and at the end of the first 2 months after the event. METHOD: Fifty patients with cardiac arrest induced by ACS and 31 patients with acute myocardial infarction (AMI) who did not require cardioversion or cardiopulmonary resuscitation were enrolled in the study, as were 40 healthy volunteers. The patients were divided into three groups based on duration of cardiac arrest (<5 min, 5-10 min and >10 min). Blood samples were collected for thyroid-stimulating hormone (TSH), tri-iodothyronine (T3), free T3, thyroxine (T4), free T4, troponin-I and creatine kinase-MB measurements. The blood samples for TFTs were taken at 72 hours and at 2 months after the acute event in the cardiac arrest and AMI groups, but only once in the control group. RESULTS: The T3 and free T3 levels at 72 hours in the cardiac arrest group were significantly lower than in both the AMI and control groups (P < 0.0001). On the other hand, there were no significant differences between T4, free T4 and TSH levels between the three groups (P > 0.05). At the 2-month evaluation, a dramatic improvement was observed in T3 and free T3 levels in the cardiac arrest group (P < 0.0001). In those patients whose cardiac arrest duration was in excess of 10 min, levels of T3, free T3, T4 and TSH were significantly lower than those in patients whose cardiac arrest duration was under 5 min (P < 0.001, P < 0.001, P < 0.005 and P < 0.05, respectively). CONCLUSION: TFTs are significantly altered in cardiac arrest induced by ACS. Changes in TFTs are even more pronounced in patients with longer periods of resuscitation. The changes in the surviving patients were characterized by euthyroid sick syndrome, and this improved by 2 months in those patients who did not progress into a vegetative state.

Cardiopulmonary Resuscitation↗