The Metabolism of Cortisol in Hyperthyroidism and Cushing's Syndrome.

Since 50 to 70% of the secreted cortisol is excreted in the urine as conjugated metabolites within 24 hrs., determination of urinary total 17-OH-CS as PorterSilber chromogen does not always indicate the true rate of adrenal cortisol secretion. Adrenal cortisol secretion in hyperthyroidism and Cushing's syndrome has been reported to be greater than in normal. (Gray et al., 1962; Hellmann et al., 1961). An increased metabolic rate of cortisol demonstrated in vivo (Hellmann et al., 1961) as well as in vitro (McGuire and Tomkins, 1959) in hyperthyroidism, is probably due to a specific effect of thyroid hormones directly or indirectly on the enzyme involved in the steroid metabolism in the liver . Such increased production of cortisol in hyperthyroidism has been considered to be the result of passive response to accelerated cortisol turnover, while that in Gushing's syndrome probably is the result of active adrenal hypersecretions. In this study metabolic patterns of the secreted cortisol and administered cortisol-4-14C or cortisone-4-14C were studied in patients with hyperthyroidism and Cushing's syndrome.