Evaluation of a new free-thyroxin assay.

Wellby, M.L.; Guthrie, L.D.; Reilly, C P

doi:10.1093/clinchem/27.12.2022

Cited by 21 publications

(2 citation statements)

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“…Serum free thyroxine concentrations and the derived ratio of thyroxine to thyroxine binding globulin (an indirect index of free thyroxine) were 1800 and 320 , lower, respectively, in the group given oestrogen compared with the controls (table II). 59-2 (3)(4)(5)(6)(7)(8)(9) Years since menopause Total thyroxine (nmol/l) 133-2 (27-4) 99-6 (22-3) p< 0-001…”

Section: Patients Methods and Resultsmentioning

confidence: 99%

Reduced serum free thyroxine concentration in postmenopausal women receiving oestrogen treatment.

Abdalla¹,

Hart²,

Beastall³

1984

BMJ

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Thyroid hormone state was assessed in a group of postmenopausal women who had received long term treatment with oestrogen. Serum concentrations of total thyroxine, triiodothyronine, and thyroxine binding globulin were raised compared with those in a control group given placebo; serum concentrations of thyroid stimulating hormone did not differ between the groups. Oestrogen treatment resulted in a significant decrease in the serum free thyroxine concentration and in the ratio of thyroxine to thyroxine binding globulin, which supports the view that oestrogen is the causative factor of the physiological reduction in free thyroid hormone during pregnancy. IntroductionIt has long been maintained that free thyroxine and free triiodothyronine represent the biologically active forms of thyroid hormones in plasma and that measurements of these fractions most accurately reflect the true state of the thyroid hormone target issue. Thus the fact that free thyroxine and triiodothyronine concentrations are decreased during pregnancy, a time of increased metabolic rate, is somewhat surprising.'-9 Such changes in serum free thyroxine concentrations have not been seen in subjects taking conventional oral contraceptives.' 4 iIn an attempt to establish whether the changes in serum free thyroxine concentrations during pregnancy are related solely to oestrogen or are brought about by some other facet of pregnancy we studied the thyroid state of a group of postmenopausal women who had undergone oophorectomy and were receiving long term replacement treatment with either oestrogen or a placebo.

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Section: Patients Methods and Resultsmentioning

confidence: 99%

Reduced serum free thyroxine concentration in postmenopausal women receiving oestrogen treatment.

Abdalla¹,

Hart²,

Beastall³

1984

BMJ

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“…By substituting Equations (2) (4) (5) and (6) in Equation (1), then the free thyrox- In addition to their important physiologicand therapeutic implications, these theoretical observations would suggest that for optimum diagnostic sensitivity, the measurement of serum FT 4 is probably well suited for cases of hyperthyroidism, but it may be inferior to TT 4 assay in hypothyroidism.…”

Section: Physicochemkal Interactionsmentioning

confidence: 99%

Deprecating the Diagnostic Significance of Free Thyroxine Levels in Human Serum

Al-Awqati

Hassan

1988

Ann Clin Biochem

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SUMMARY. Prime diagnostic importance has been postulated for the measurement of free thyroxine in human serum. During the past decade various innovative and routinely applicable techniques have been developed for its assay, and claims for their superior performance in clinical practice have subsequently been made. However, in our opinion, based on current literature concerning thyroxine metabolism together with basic information about the physicochemical characteristics that govern its intravascular distribution, it seems appropriate to indicate caution against overestimating the diagnostic sensitivity attributed to free thyroxine measurement irrespective of assay methodology and its conceptual elegance.

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