Effects of Estrogen and Testosterone on Circulating Thyroid Hormone*

Effects of Anabolic Steroids Upon Circulating Thyroid Hormones

“…Most of the steroids, the administration of which has been reported to lead to a decrease in the serum PBI concentration, are androgenic to a varying degree; these include testosterone (9,11,12), 17a-methyl-testosterone (12), 17a-methyl-19-nortestosterone (9), corticosteroids (13), and 17a-ethyl-19-nortestosterone and Al,17o!-methyltestosterone, as reported here. There would seem to be little doubt that the PBI-lowering activity of these substances does not parallel androgenicity.…”

Free thyroxine in human serum: simplified measurement with the aid of magnesium precipitation.

“…This is well illustrated in the euthyroid pregnant subjects with the characteristic elevation of PBI attributable to increased TBG concentration (1,(17)(18)(19)(20)(21)(22)(23)(24), but a low per cent free thyroxine, giving a computed free thyroxine iodine concentration in the low normal range. It is considered likely that the physiological activity of thyroxine depends upon the concentration of unbound hormone.…”

Clinical and Physiological Observations in a Patient With an Idiopathic Decrease in the Thyroxine-Binding Globulin of Plasma*

“…In vivo correlations have mainly required the use of pharmacological agents to alter the thyroxine-binding capacity of TBG, associated effects on the peripheral metabolism of labeled T4 being then determined. Diethylstilbestrol and natural estrogens, for example, increase the binding capacity of TBG ' (13,16) and decrease the fractional rate of turnover of the hormone (13,17), while methyltestosterone produces converse effects (18). These in vivo observations, while consistent with the major hypothesis, have not been entirely conclusive because of the possibility that the agents employed might directly affect cellular mechanisms for the disposal of hormone.…”