Synergistic effects of growth hormone therapy on plasma levels of 11-deoxycortisol and cortisol in growth hormone-deficient children.

We have studied the response of blood levels of progesterone, 17-hydroxyprogesterone, 11-deoxycortisol, and cortisol to acute ACTH stimulation in children with isolated GH deficiency. Patients with isolated GH deficiency had generally higher levels of 11-deoxycortisol and lower levels of cortisol than controls both before and after ACTH stimulation. The steroid levels were almost completely restored to control levels after 3 months of treatment with GH. The pre-ACTH treatment levels of 11-deoxycortisol and cortisol were low in patients with both GH and ACTH deficiencies before and during GH therapy. Therefore, GH alone did not appear to have any effect on the hydroxylation of 11-deoxycortisol to cortisol. Before GH therapy, ACTH increased the concentrations of the two steroids. After GH therapy was started, the increase in 11-deoxycortisol was much smaller, but the increase in cortisol was much larger than before therapy. These results suggest a synergistic effect of GH on ACTH action on the biosynthesis of cortisol in the adrenals. Variations in the levels of 11-deoxycortisol and cortisol during hormonal manipulations lead to the identification of the mitochondrial hydroxylation of 11-deoxycortisol as one of the possible sites of action of GH.