PRODUCTION-RATE AND MEAN PLASMA CONCENTRATION OF CORTISOL IN HYPERTHYROIDISM

  • 1 January 1976
    • journal article
    • research article
    • Vol. 37  (5) , 331-345
Abstract
Adrenocortical function was studied in 23 patients with hyperthyroidism. The half-life of 3H-cortisol was significantly shortened; metabolic clearance rate was about twice increased, and production rate of cortisol was significantly increased in hyperthyroidism. Mean plasma concentration was unmodified. After return to a euthyroid state, all values were normalized in 7 patients. The increased metabolic clearance rate was the consequence of hepatic enzymes activation (5 .alpha.-reductase and 11 hydroxysteroid deshydrogenase) secondary to thyroid hormone excess, as demonstrated by urinary 17 OHCS [17-hydroxycorticosteroid] chromatographic studies. The hypothalamohypophyseal-adrenal system was stimulated to maintain a normal plasma concentration. Since the mean plasma concentration was normal despite the increased production rate, changes were probably due to increased catabolism rather than to the central effect of thyroid hormones.

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