Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Thyroid Function Tests”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 631 records · Page 35Linked to original sources
PubMed1979

A study of age-dependent changes in thyroid function tests in adults.

Total serum thyroxine (T4), triiodothyronine (T3), T3 resin uptake (T3U), thyrotrophin (TSH), and reverse T3 (rT3) were measured in 209 healthy adults 20--89 yr old. Mean T4 values for men were stable throughout life, but in females under age 60, T4 values were significantly higher than in older women. Values for T3U in males were significantly higher than in females throughout all decades, although females had a significant increase in T3U after age 60. TSH values increased significantly in females over age 60. Throughout all decades, males had stable TSH levels that were slightly higher than the female results before age 60 and lower thereafter. Mean serum T3 declined similarly for both sexes with increasing age, although not to the extent previously reported. Men had significantly higher mean rT3 values over all decades than females, although female rT3 levels decreased after age 50 whereas males maintained stable values. The physiologic reasons for these findings may be due to sex-related changes in binding proteins and alterations in metabolic clearance rates, production, and degradation of these hormones with increasing age.

Adult↗
PubMed1997

Abnormal thyroid function tests in infants with congenital hypothyroidism: the influence of soy-based formula.

OBJECTIVE: To assess the etiology of hyperthyroxinemia or hyperthyrotropinemia in infants with congenital hypothyroidism who are on replacement therapy with L-thyroxine. METHODS: These infants were treated with recommended doses of L-thyroxine following the diagnosis of congenital hypothyroidism. Because of hyperthyroxinemia (2 patients) and hyperthyrotropinemia (1 patient), medication compliance and dietary practice (formula type, age of introduction, and discontinuation or change of the formula) were assessed. Clinical evaluation was also performed. RESULTS: Elevated thyroxine level in 2 infants was associated with discontinuation of soy formula 4 weeks previously; reduction of L-thyroxine dose normalized serum levels in both of these infants. In the third infant, who received soy formula from 1 week of age, TSH remained elevated despite incremental L-thyroxine doses of 19 micrograms/kg/day; discontinuation of soy formula was followed by normalization of the TSH in 3 weeks and helped attain a subsequent decrement of L-thyroxine dose to 8.6 micrograms/kg/day. Neither the hyperthyroxinemia nor hyperthyrotropinemia in these infants was associated with any adverse behavioral-developmental consequence. CONCLUSION: When initiating soy-formula feeding in infants with congenital hypothyroidism, the L-thyroxine dose should be increased because of significant reduction in intestinal absorption: conversely, when soy feeding is discontinued, the L-thyroxine dose should be decreased.

Congenital Hypothyroidism↗
PubMed1975

Thyroid-function tests in diphenylhydantoin-treated patients.

We compared the free-thyroxine index in normal adults and in euthyroid patients taking diphenylhydantoin. All subjects had normal serum thyrotropin concentrations. Serum thyroxine concentrations were determined by two commonly used competitive protein-binding assays, which yielded slightly different values, but which consistently showed the same degree of decrease in mean serum thyoxine concentration in drug-treated patients as compared to the normal subjects. When 14C-labeled diphenylhydantoin was added to serum before the assay, it was separated from thyroxine in the Ames method, whereas by the Murphy-Pattee method both drug and thyroxine were extracted together. Thus, the decrease in serum thyroxine concentrations during diphenylhydantoin therapy cannot be the result of drug interference with the binding of thyroxine to binding proteins in the assays. Triiodothyronine uptake, evaluated by two methods, was identical in the two groups. The free-thyroxine indexes for all normal persons were within the manufacturer's normal range, but 21% of the drug-treated patients had subnormal indexes by the Ames method; the indexes as measured by the Murphy Pattee method were in the lower half of the normal range. Because the triiodothyronine uptake was unaffected by the drug treatment, the decreases in the indexes must have resulted from the lower serum thyroxine concentrations. We conclude that the free-thyroxine index may not provide a valid estimate of either the clinical status or the free-thyroxine concentration in patients taking diphenylhydantoin.

Adult↗
PubMedDate not supplied

Thyroxine binding globulin and thyroid function tests in patients with hepatocellular carcinoma.

To determine the prevalence of elevated serum concentrations of thyroxine binding globulin (TBG) in patients with hepatocellular carcinoma (HCC) and the influence of the associated cirrhosis, TBG was measured in 39 patients with HCC, 22 with and 17 without cirrhosis, in 20 patients with cryptogenic macronodular cirrhosis but without HCC, and in 40 matched controls. The mean serum TBG concentration in the patients was 34.5 +/- 17.7 microgram per ml, compared to 21.4 +/- 6.8 microgram pr ml in controls and 20.5 +/- 6.3 microgram per ml in cirrhosis without HCC (p less than 0.01). The presence or absence of cirrhosis in the HCC patients did not significantly influence the frequency with which elevated TBG levels were found; levels were normal in every subject with cirrhosis and no HCC. The mean thyroxine (T4): TBG ratio was 5.58 +/- 1.78 in controls and was reduced in HCC patients with both elevated (3.33 +/- 0.80, p less than 0.001) and normal TBG values (4.39 +/- 1.90, p less than 0.05), and in cirrhotics without HCC (4.29 +/- 1.01, p less than 0.01). T4 and TBG concentrations correlated significantly in controls, in HCC patients with elevated TBG, and in the cirrhotics without HCC. It is concluded that in patients with HCC (i) TBG levels may be elevated both in the presence or absence of cirrhosis; (ii) there is reduced binding of T4 TBG, and (iii) a low T4:TBG ratio excludes the diagnosis of hyperthyroidism in the presence of high T4 levels. TBG levels are normal in patients with cryptogenic macronodular cirrhosis without HCC.

Adult↗
PubMed2001

Reference ranges for thyroid function tests in premature infants beyond the first week of life.

OBJECTIVES: To establish reference ranges for the more sensitive assays of thyrotropin and the best available assays of free thyroxine in premature infants after the first week of life. STUDY DESIGN: Free thyroxine measurements by direct equilibrium dialysis and thyrotropin measurements by third generation immunometric assay were measured in 120 healthy premature infants 25 to 36 weeks' gestation at birth and every 3 weeks until hospital discharge. Infants were stratified by postconceptional age. Differences in free thyroxine and thyrotropin levels among groups were determined by ANOVA. Correlations between hormone measurements and gestational and postnatal ages were sought by linear regression analysis. Reference ranges were determined as arithmetic (free thyroxine) and geometric (thyrotropin) mean+/-2 SD ranges. RESULTS: From 120 infants, 164 samples were obtained and grouped by postconceptional age at sampling. Free thyroxine was not different among postconceptional age groups and did not correlate with gestational or postnatal age. The free thyroxine reference range based on these data was 10 to 33 pmol/l (0.8 to 2.6 ng/dl). Thyrotropin did not correlate with gestational age. There was a clinically trivial but statistically significant (r(2)=0.03, p<0.05) correlation of thyrotropin with postnatal age. The thyrotropin reference based on these data was 0.8 to 12 mU/l. CONCLUSIONS: Free thyroxine was closely regulated in these premature infants and levels were similar to those in older children and adults, once the natal surge in thyrotropin has subsided. After the first week of life a single range for each hormone appeared appropriate for all premature infants until 40 weeks postconceptional age.

Female↗
PubMed1976

Observations on thyroid function tests in the elderly.

One hundred elderly men and women living in old people's homes and 95 in a long-stay geriatric hospital were investigated for thyroid function by measuring the serum thyroxine, T-3 uptake and calculating the free thyroxine index. The values obtained were found to be within the normal adult range in 97% of the subjects studied. No significant correlation was found between albumin and T-3 uptake, except in men in hospital.

Aged↗
PubMed1990

Coexisting hyperthyroidism and hyperparathyroidism: two cases report.

To examine the biochemical changes in coexisting hyperthyroidism and hyperparathyroidism, we have studied two female cases in our medical center. Both patients received biochemistry study, thyroid function test, thyroid autoantibody determination, parathyroid function tests and thyroid scan. They all had increased thyroid function. The concentration of parathyroid hormone was found to elevate in both cases. After thyroid function turned normal, hypercalcemia was still present. Both patients underwent neck operation. Parathyroid adenoma was found in both cases. The pictures of thyroid pathology showed diffuse hyperplasia in one case and lymphocytic thyroiditis in the other case.

Adenoma↗
PubMed1998

Pulmonary tuberculosis and its therapy do not significantly affect thyroid function tests.

Basal thyrotropin, total thyroxine, total tri-iodothyronine and free tri-iodothyronine were measured in 30 HIV-negative patients with focal pulmonary tuberculosis upon starting and after one and two weeks of isoniazid, rifampicin and pyrazinamide therapy. Rapid and statistically significant elevations in free tri-iodothyronine and total tri-iodothyronine were noted after the first and second week of treatment respectively. For most patients, however, hormone levels remained within normal limits throughout the study. Overall, the effects of pulmonary tuberculosis and of its therapy on the thyroid function parameters examined, in otherwise healthy individuals, appear to be minimal.

Adult↗
PubMed1991

The effects of drugs on tests of thyroid function.

Many drugs affect tests of thyroid function through alterations in the synthesis, transport and metabolism of thyroid hormones, as well as via influences on thyrotrophin (TSH) synthesis and secretion. Despite effects on circulating thyroid hormone and TSH levels, few drugs result in important changes in clinical thyroid state, but difficulty in interpretation of thyroid function tests often results. Commonly prescribed drugs including anti-convulsants, non-steroidal anti-inflammatory drugs, beta-adrenoceptor antagonists, steroid hormones and heparin may result in abnormal thyroid function tests in the absence of clinical features of thyroid dysfunction. In contrast, lithium and iodine containing drugs, including radiographic contrast agents and amiodarone, may result rarely in overt thyroid disease.

Adrenal Cortex Hormones↗
PubMed1986

Effect of fenoprofen on thyroid function tests.

We observed that a few patients taking the anti-inflammatory drug fenoprofen showed increases in total and free T3 serum levels without convincing evidence of an associated thyrotoxicosis. To confirm these findings, two volunteers were given fenoprofen for two weeks. Within this time total T3 levels almost doubled and free T3 levels increased threefold. Administration of fenoprofen did not have any measurable effect on T4 or TSH estimations. Cross-reactivities of fenoprofen and 4'-hydroxyfenoprofen were studied with antisera from various total and free T3 assays. Results show that the metabolite cross-reacts with the antisera from Amerlex total and free T3 assay kits. A lesser degree of interference was observed with the Corning total and free T3 assays. 4'-hydroxyfenoprofen had no effect on an 'in house' total T3 assay. Laboratories should therefore be aware of the possibility that their assay may be subject to interference by fenoprofen or its metabolites while clinicians should be aware of this interference in order that they may avoid unnecessary and harmful treatment.

Adult↗