Effects of Long-Term Growth Hormone Therapy on Adrenal Steroidogenesis in Turner Syndrome

It has been shown that growth hormone (GH) and insulin-like growth factor-1 (IGF1) enhance steroidogenesis responsiveness to ACTH in cultured adrenal cells. To investigate the GH effect on adrenal steroidogenesis in non-GH-deficient subjects, we studied 9 girls with Turner syndrome (chronological age 5.5–7.2 years; bone age 5–7 years). In all subjects an ACTH test (Synacthen depot, 0.25 mg i.v. with blood samples at 0 and 60 min) was performed basally at 8–9 a.m. and 6 months after GH therapy (1 IU/kg/week). 17-Hydroxypregnenolone (17PGN), 17-hydroxyprogesterone (17OHP), dehydroepiandrosterone (DHA), its sulfate (DHA-S), androstenedione and cortisol were evaluated by radioimmunoassay. Two groups of normal girls were selected as controls: group A age-matched the patients at the start of the study, and group B age-matched the patients at the end of the study. The responsiveness of each hormone to ACTH was expressed as the difference between stimulated and basal values. A p value of < 0.01 was considered to indicate significance. There were no significant differences between pre- and posttreatment basal values of 17PGN, 17OHP, DHA, androstenedione and cortisol in the Turner syndrome patients, whereas a significant increase was observed for basal DHA-S (1.57 ± 0.31; 1.89 ± 0.43 µmol/l, p < 0.01). Comparison of increments before and after GH treatment showed a significant increase in responsiveness to ACTH after GH therapy DHA (p < 0.01). The increase in 17PGN was evident (p < 0.02), but the established significant p value was not reached. No differences for 17OHP, androstenedione and cortisol were found. The stimulated 17PGN/17OHP ratio was significantly higher (p < 0.01) after GH, whereas the 17OHP/androstenedione ratio was considerably lower, but the p value was