Effect of treatment with sodium valproate and diazepam on plasma corticotropin in Nelson's syndrome.

Six patients with Nelson's syndrome were given sodium valproate with or without diazepam for 3 or 5 weeks. Initial high plasma adrenocorticotropic hormone (ACTH) concentrations were greatly reduced by treatment and returned to high levels when treatment was stopped. Diazepam did not add significantly to the effects of sodium valproate alone. Three patients reported a decrease in the severity and frequency of headaches while on sodium valproate. In five patients abnormal skin pigmentation was reduced. Sodium valproate is a gamma-aminobutyric acid (GABA) transaminase inhibitor and it is suggested that the drug raises GABA levels in the hypothalamus and that this is responsible for the reduction in ACTH secretion. The data are consistent with the hypothesis that Nelson's syndrome is a neuroendocrine disease caused by a deficiency in the hypothalamic GABA-ergic system.