Growth hormone response to physical exercise in growing patients with classic congenital adrenal hyperplasia

Glucocorticoid over-treatment in children with congenital adrenal hyperplasia (CAH) may suppress GH secretion and growth. Aims of our study were: 1) to evaluate post-exercise GH response in patients affected by CAH due to 21-hydroxylase deficiency, in comparison with a group of healthy subjects; 2) to investigate the relationship between the hormonal markers of adequate steroid therapy and GH secretion. We evaluated GH secretion every 6 months in 20 young CAH patients (8 girls, 12 boys). Mean follow-up was 4.6+/-0.9 yr (107 tests performed, 5.35+/-2.05 repeated tests for each patient). Forty-four healthy subjects (25 boys, 19 girls) were selected as a control group. The range of post-exercise GH peak was very wide, but medians were not statistically different in cases and controls (p=0.570). Multivariate analysis showed that post-exercise GH peak was not related to age (p=0.743), gender (p=0.296) or pubertal status (p=0.440) in both groups. GH increase from baseline showed the same behavior (p=0.265, 0.639 and 0.105, respectively). In CAH patients, GH peak and GH increase were both directly related to 17-OH-progesterone levels [GH peak: p=0.032--95% confidence interval (CI): 0.01-0.34--beta=0.18; GH increase: p=0.008--95% CI: 0.06-0.35--beta=0.20]. The negative effect of glucocorticoid therapy on GH secretion seems to be dominant in CAH. The most effective approach to adjust treatment remains monitoring growth. Relying on hormonal markers to adequate steroid therapy may result in over-treatment, GH suppression, and finally poor linear growth.