Pubertal growth spurt induced by human chorionic gonadotropin in hypogonadotropic growth hormone-deficient children

Eight hypogonadotropic growth hormone-deficient children were treated with human chorionic gonadotropin (HCG) while they continued to receive a fixed dose of HGH for a one year period. They were observed for changes in somatomedin C (IGF-I) and height increase velocity. Mean somatomedin C was 0.79 +/- 0.30 U/ml in normal prepubertal children (N = 7) and 0.78 +/- 0.31 U/ml in prepubertal normal short children (N = 22). At pubertal stage 3, somatomedin C was 2.21 +/- 1.23 and 2.05 +/- 0.44 U/ml in normals (N = 5) and in normal short children (N = 7), respectively. When 3000-5000 units/week of HCG were given to each of the 8 hypogonadotropic growth hormone-deficient children who were receiving HGH at a mean dose of 0.33 +/- 0.05 IU/kg/week, testosterone increased from less than 0.3 ng/ml to more than 5 ng/ml at 6 months in 3 cases and at 12 months in 2 cases, while the testosterone concentration was less than 3.5 ng/ml in the remaining 3 cases. The rate of height increase rose significantly (p less than 0.001) from 5.2 +/- 1.0 to 9.3 +/- 1.4 cm/year mimicking the normal pubertal growth spurt. However, the mean somatomedin C concentration was 0.44 +/- 0.23 before therapy, 0.33 +/- 0.30 at 6 months and 0.31 +/- 0.14 U/ml at 12 months after the start of HCG therapy. It is concluded that the pubertal growth spurt induced by HCG in hypogonodotropic GH-deficient male children is not mediated by the increase in somatomedin C production.