Concentration of thyroxine-binding globulin: value of direct assay.

Burr, W. A.; Ramsden, D.; Evans, S. E.; Hogan, T. C.; Hoffenberg, R.

doi:10.1136/bmj.1.6059.485

Cited by 84 publications

(28 citation statements)

References 19 publications

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“…This is probably a physiological response to maintain the free thyroxine at a constant level. The finding of a close correlation between the T 4:T3-uptake ratio and the T 4:TBG ratio is as expected and has been reported elsewhere (Burr et al, 1977;Lecureuil et al, 1978). The concomitant finding that the T 4:TBG ratio gives values for the ill, contraceptive, and pregnant groups which lie in the euthyroid range, whereas the T4:T 3-uptake ratio gives values in the abnormal range, indicates a further use for the TBG assay.…”

Section: T:tbgv T:t-uptakesupporting

confidence: 65%

“…The concomitant finding that the T 4:TBG ratio gives values for the ill, contraceptive, and pregnant groups which lie in the euthyroid range, whereas the T4:T 3-uptake ratio gives values in the abnormal range, indicates a further use for the TBG assay. The findings in the David R. McDowell contraceptive and pregnancy groups may be explained by the previously mentioned lowered increase in serum Ts-uptake values in relation to increasing serum TBG concentrations at high levels ofTBG (Burr et al, 1977). In the acutely ill group the serum levels of TBG are decreased along with those of thyroxine-binding pre-albumin and albumin (increased catabolic state).…”

Section: T:tbgv T:t-uptakementioning

confidence: 79%

“…A retrospective examination of the patients studied revealed two decreased levels (less than 6 mg/l) and two increased levels (greater than 50 mg/l), Serum TBG levels are well correlated with T3-uptake levels, although at higher values the rate of increase of Ts-uptake with increasing TBG concentration is lowered. This explains why the FTI gives inappropriately elevated levels in patients who are taking the contraceptive pill, are on oestrogen therapy, or are pregnant (Burr et al, 1977). Clearly, as an indirect assay of TBG, Ts-uptake fails to fulfil this function at high concentrations.…”

Section: T:tbgv T:t-uptakementioning

confidence: 99%

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An Evaluation of Serum Thyroxine Binding Globulin as a Routine Test of Thyroid Function

McDowell

1979

Ann Clin Biochem

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SUMMARY 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.The assays commonly used to detect thyroid dysfunction are a combination of serum thyroxine (T4), tri-iodothyronine uptake (T3-uptake), and free thyroxine index (FT!) as first-line tests, with serum T3, thyroid stimulating hormone (TSH), and the thyrotrophin releasing hormone (TRH) stimulation test to augment the diagnosis. With these tests it is possible to confirm the thyroid status of the majority of patients (Pain and Duncan, 1976;Evered et al., 1978).In a proportion of patients, especially those who are on antidepressant therapy, are taking the contraceptive pill, are pregnant, have severe nonthyroidal disease, or are elderly, the above tests become more difficult to interpret because of abnormal levels of the thyroid hormone binding proteins (Oppenheimer, 1968). The derived index, FIT, was initially reported to compensate for abnormal levels of the thyroxine-binding proteins (Howorth and MacLagen, 1969), but it has become increasingly recognised that this is not always correct, and reliance on this index may lead to a false diagnosis of thyroid status (Premachandra et al., 1976). A direct assay of thyroxine binding globulin (TBG) in serum was first described by Freeman and Pearson in 1969, soon followed by the first radioimmunoassay (Levy et al., 1970). It was the purpose of this study to investigate the relationships of TBG to the other thyroid parameters and to ascertain whether its routine use aids the differentiation of the thyroid disorders. Patients and methodsThyroid status was determined using assays of serum 'Present address: Department of Chemical Pathology, Hope Hospital, Eccles Old Road, Salford M6 8HD T4, T 3-uptake, and FT!, followed by assays of serum T3, TSH, or a TRH-stimulation test where appropriate. Details of age, sex, therapy, and clinical diagnosis were recorded at the same time. The patients were then classified as follows:1 Acutely ill: patients having severe non-thyroidal diseases (eg, congestive cardiac failure, myocardial infarction, severe diabetes, carcinoma, renal failure).2 Contraceptive pill users: women between the ages of 16 and 40 years who are currently taking any form of oral contraceptive (for periods greater than six months).3 Pregnant: women between the ages of 16 and 40 years and at between 20 and 40 weeks' of pregnancy.4 Borderline hypothyroid: patients having either one result in the hypothyroid range or all results outside 75 % of normal limits.5 Hypothyroid: patients having all results in the hypothyro...

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Section: T:tbgv T:t-uptakesupporting

confidence: 65%

Section: T:tbgv T:t-uptakementioning

confidence: 79%

Section: T:tbgv T:t-uptakementioning

confidence: 99%

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An Evaluation of Serum Thyroxine Binding Globulin as a Routine Test of Thyroid Function

McDowell

1979

Ann Clin Biochem

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“…However, data about serum levels of hCT is conflicting 3 . Some studies could not detect it, while others have reported significant level of circulating hCT in pregnancy 4,5 found to correlate negatively with TSH. This elevated hCG levels during the 1st trimester and the lower TSH level often observed early in pregnancy do raise the possibility of some degree of thyroid hyper function in early pregnancy.…”

Section: Introductionmentioning

confidence: 89%

Thyroid Stimulating Hormones (TSH & hCG) and thyroid functions in normal pregnancy

Rahman

Chowdhury

2017

KYAMC j.

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Hormonal changes and maternal demands during pregnancy result in marked changes in maternal thyroid activity. It has been suggested that the thyrotropic effect of hCG in pregnancy increases thyroid activity in addition of thyrotropic effect of TSH. To compare the serum levels of thyroid stimulators (hCG & TSH) and thyroid hormones (T3 & T4)) in normal pregnant women and thus to clarify the role of hCG & TSH on thyroid function in pregnancy, we measured serum hCG, TSH, total T3 & T4 and free T3 & T4 concentrations in the serum samples of 32 pregnant women in their different trimesters and in the serum samples of 22 non-pregnant normal female control. Serum total T3 & T4 were significantly elevated throughout pregnancy in comparison with controls. Free T4 level was elevated at 1st trimester but reduced in 2nd and 3rd trimesters. The free T3 levels were remained unchanged throughout pregnancy and no significant change in pregnancy than non pregnant control. Serum TSH levels were significantly lower at 1st trimester compared to 2nd and 3rd trimester of the pregnancy. Serum hCG levels were highest in 1st trimester. We conclude that hCG, as a weak thyroid stimulator, causes moderate increase in free thyroid hormone levels in 1st trimester which in turn causes a moderate reduction in TSH levels in early pregnancy.KYAMC Journal Vol. 6, No.-2, Jan 2016, Page 623-626

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“…Besides normal thyroid stimulating hormone (TSH), there is evidence for presence of other thyroid stimulators like human chorionic gonadotropin hormone (hCG). There is also evidence for increase concentration of thyroxine binding globulin (TBG) which is induced by increased estrogen production in pregnancy 2,3,4 . In normal pregnancy increased serum concentration of TBG results in increased serum concentration of total T4 and to a lesser extend of total T3.…”

Section: Introductionmentioning

confidence: 99%

Thyroid Function in Normal Pregnancy

2017

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Hormonal changes and metabolic demands during pregnancy result in alteration in the physiological and biochemical parameters of thyroid function. Among the many physiological alterations which may occur during pregnancy are thyroid enlargement, increased thyroid capability for iodine uptake and increase in serum thyroxine and tri-iodothyronine concentration. However these findings are not usually associated with symptoms of hyperthyroidism. To clarify the changes, a study was undertaken in Rajshahi Medical College Hospital when serum specimens were collected from individual woman at different stages of normal pregnancy and women married but non pregnant. Among the study subjects, 22 women were in their 1st trimester, 20 women were in their 2nd trimester, 32 women were in their 3rd trimester of normal pregnancy and 10 women were married but non pregnant. We have measured serum levels of total and free thyroxine (TT4 & FT4) and total and free triiodothyronine (TT3 & FT3 ) by using RIA. During the 1st trimester of pregnancy serum FT4 and FT3 concentrations are significantly higher than in non pregnant women and women in 3rd trimester. The concentration of FT4 and FT3 progressively declined as the pregnancy advanced and are to control level in the 3rd trimester. The mean serum TT4 and TT3 are significantly elevated throughout pregnancy in comparison to control.KYAMC Journal Vol. 4, No.-2, Jan 2014, Page 415-418

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Concentration of thyroxine-binding globulin: value of direct assay.

Cited by 84 publications

References 19 publications

An Evaluation of Serum Thyroxine Binding Globulin as a Routine Test of Thyroid Function

An Evaluation of Serum Thyroxine Binding Globulin as a Routine Test of Thyroid Function

Thyroid Stimulating Hormones (TSH & hCG) and thyroid functions in normal pregnancy

Thyroid Function in Normal Pregnancy

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