EFFECT OF HYPERCORTISOLISM AND ACTH ON THE METABOLISM OF CORTISOL

The effects of hypercortisolemia and ACTH on the metabolism of cortiso l in congenital adrenal hyperplasia, Gushing's syndrome, and exogenous ACTH and cortisol administration were investigated by analysis of the respective urinary tetrahydro-metabolites of cortisol (THF and aTHF) and cortisone (THE) by capillary gas chromatography. The results for t he patients with congenital adrenal hyperplasia establish that ACTH hy persecretion in the absence of an associated marked elevation of plasm a cortisol does not cause inhibition of the 11 beta-OHSD enzyme. In co ntrast elevated plasma cortisol levels (adrenal adenoma or intravenous cortisol administration) in the presence of suppressed ACTH secretion leads to significant inhibition of the peripheral conversion of corti sol to cortisone. The latter results are equivalent to the mode of cor tisol metabolism noted during clinical states of ACTH hypersecretion a nd hypercortisolemia (Gushing's disease, ectopic ACTH syndrome and ACT H administration). The overall findings provide convincing evidence th at ACTH hypersecretion is not associated with specific in vivo inhibit ion of 11 beta-OHSD enzyme activity.