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At least 649 records · Page 36Linked to original sources
PubMed1986

Pharmacology of propylthiouracil (PTU) in pregnant hyperthyroid women: correlation of maternal PTU concentrations with cord serum thyroid function tests.

Previous studies have characterized the pharmacology of propylthiouracil (PTU) in normal and hyperthyroid subjects, but there is little information available regarding PTU pharmacokinetics in pregnant hyperthyroid women. We investigated the serum PTU response to an oral dose of PTU in six hyperthyroid pregnant women both ante- and postpartum. The serum PTU profile during the third trimester of pregnancy was qualitatively similar to that in nonpregnant subjects, but serum PTU concentrations were consistently lower in the late third trimester compared with postpartum values. Cord serum PTU concentrations were consistently higher than simultaneously obtained maternal serum PTU concentrations, suggesting slower PTU clearance in the fetus. There was a significant inverse correlation (r = -0.92; P = 0.026) between the maternal serum PTU area under the curve in the third trimester and the cord serum free T4 index.

Adult↗
PubMed1985

The influence of age and sex on tests of thyroid function.

Serum concentrations of total thyroid hormones, thyroid hormone binding proteins, free thyroid hormones and thyroid stimulating hormone (TSH) were measured in a large group of healthy normal subjects (n = 218) to determine the influence of age and sex on tests of thyroid function. No effect of age on measurements of total thyroxine (T4), total triiodothyronine (T3) or reverse T3 was evident. Concentrations of free T4, free T3 and TSH were similarly unaffected, suggesting that increasing age alone does not significantly influence thyroid hormone measurements. There was, however, a rise in thyroxine-binding globulin (TBG) concentration with increasing age and a fall in thyroxine-binding prealbumin (TBPA). An influence of sex on tests of thyroid function was clearly evident. Levels of total T4, total T3, free T4 and the T4: TBG ratio were lower in women between 16 and 49 years than in men, despite an increase in TBG. Lower levels of free T3 were confined to the group of women aged 16-29 years. TSH values were unaffected by sex. These results suggest that sex hormone status in the pre-menopausal female subject may result in an increase in TBG concentration, and in addition may have an opposing effect on circulating thyroid hormone concentrations.

Adolescent↗
PubMed1997

Biochemical testing of thyroid function.

Various published guidelines recommending serum thyrotropin (TSH)-first thyroid testing are outlined. The entities called "subclinical hypothyroidism" and "subclinical hyperthyroidism" are defined on the basis of abnormal TSH concentrations and normal values of other biochemical thyroid tests. The controversies about follow-up and treatment of these disorders are discussed. The laboratory experience of Mayo Clinic Rochester in using TSH-first thyroid testing and the subsequent implementation of a thyroid test ordering cascade are presented. Finally, recommendations are given for further optimizing laboratory testing for thyroid disorders.

Hyperthyroidism↗
PubMed1979

An evaluation of serum thyroxine binding globulin as a routine test of thyroid function.

Serum thyroxine binding globulin (TBG) values were correlated with other thyroid function test results and with the clinical condition in 680 patients. The estimation of serum TBG was helpful in the evaluation of thyroid status only in those patients who were either acutely ill, were taking the contraceptive pill, or were pregnant. Further, the derived index, thyroxine: TBG ratio, proved to be a better diagnostic index than the thyroxine:tri-iodothyronine uptake ratio and in many cases would have avoided the use of more expensive and time-consuming tests.

Acute Disease↗
PubMed1975

The use of the 99mTc-pertechnetate neck/thigh ratio as a test of thyroid function.

A total of 100 patients were studied by standard thyroid function tests and the 99mTc-pertechnetate neck/thigh ratio was determined. This ratio or "trapping index" correlated closely with 131I uptake. The 99mTc test should be followed by scanning at 20 minutes to distinguish diffuse from localized thyroid disease. TSH stimulation and suppression studies can be done. It is recommended that this ratio be used in place of the standard 24-hour RAIU study, as it gives the same information at a saving in time, money, and radiation exposure.

Humans↗
PubMed1972

The T 4 -free thyroxine index as a test of thyroid function of first choice.

The T(4)-free thyroxine index was used as the thyroid function test of first choice in a district general hospital for one year. Ninety-two patients were assessed both initially and at follow up by a single physician. The index agreed with clinical assessment in 69 out of 74 patients in whom diagnosis was unequivocal. There was initial doubt about thyroid status in 14 patients; after re-assessment the index agreed with status in seven cases, in three cases there is still some uncertainty, whilst the index was at variance with clinical status in four patients. Some possible causes of discrepancy between clinical thyroid status and the index are a low index in euthyroid patients due to a fall in serum thyroxine-binding prealbumin (;sick euthyroid'), a raised index in euthyroid patients due to latent thyroid heart disease, and a normal index in thyrotoxicosis due to preferential secretion of triiodothyronine.

Adult↗
PubMed1981

Free thyroxine, thyroxine/TBG ratio and other in vitro tests of thyroid function evaluated by discriminant analysis.

T4, T3, TSH, FT4 (Corning method), TBG, T3U and a diversity of free thyroid hormone indices were determined in serum from 72 reference persons and 337 patients with either thyroid diseases, TBG abnormalities, non-thyroid illnesses, or medications known to affect the results of thyroid function tests. Ninety-six per cent were 20 years or older. None of the laboratory parameters showed significant age or sex dependence, whereas systemic illness and medications frequently influenced test results. Thus the mean values of all patient groups differed significantly from those of the reference group in two or more laboratory tests, and significantly from those of the reference group in two or more laboratory tests, and significant differences were detected in 73% of the total number of 209 paired comparisons of test results between reference and patient groups. As a single parameter, free thyroxine index was found to be a marginally more efficient thyroid function discriminator than FT4, which again was more efficient than the T4/TBG ratio. However, non of these parameters were included in the combinations of laboratory tests identified as optimum by discriminant analysis. The overall optimum test combination was T4, TSH and T3U, which had an efficiency for correct thyroid function reclassification better than 98% in the total material. T3 replaced TSH in distinguishing between hyperthyroidism and euthyroidism.

Adolescent↗