ACUTE AND CHRONIC EFFECTS OF HUMAN RECOMBINANT GH (HRGH) ON ADRENAL STEROIDOGENESIS IN CHILDREN AFFECTED WITH ISOLATED GH DEFICIENCY (IGHD)

In a previous study we demonstrated that, in children affected with is olated GH deficiency, an acute high-dose human recombinant GH (hrGH) t reatment increases the 11-deoxycortisol and induces an IGF-I responsiv eness to ACTH. The aim of the present study was to reevaluate, in the same children, the adrenal and IGF-I responsiveness to ACTH after a ch ronic replacement-dose GH therapy. Ten children (seven males and three females, mean age 7 years) affected with isolated GH deficiency under went a synthetic ACTH 1-17 test before and after sc administration of human recombinant GH at a dose of 0.6 UI/kg/week for 3 months. After t herapy, the 11-deoxycortisol responsiveness to ACTH significantly decr eased compared with that observed after acute treatment (P < 0.001), a nd so it returned to baseline. No differences were detected in the res ponsiveness to ACTH of cortisol, dehydroepiandrosterone-sulphate, D4-a ndrostenedione, and 17-hydroxyprogesterone. On the other hand, the chr onic treatment induced an IGF-I responsiveness to ACTH (P < 0.001). In conclusion, our study demonstrates that, in isolated GH deficiency, r eplacement doses of hrGH do not modify the adrenal steroid basal level s or its responsiveness to ACTH, whereas both replacement and high dos es of hrGH induce an IGF-I responsiveness to ACTH.