The interaction of growth hormone, somatomedin and oestrogen in patients with Turner's syndrome.

Baseline somatomedin activity in seven of eight patients with Turner's syndrome was found to be within normal limits. Somatomedin activity readily suppressed with oestrogen administration. The overall mean serum somatomedin activity during oestrogen therapy (0.87 U/ml, SD 0.15) was significantly lower (P less than 0.005) than the mean of the control serum somatomedin activities (1.09 U/ml, SD 0.24). During oestrogen therapy, suggestive elevations of fasting growth hormone levels were noted in five of eight patients. The data indicate that oestrogenic suppression of serum somatomedin was not due to decreased growth hormone secretion and suggest the existence of a negative feedback link between somatomedin and growth hormone.