Successful treatment with sodium valproate of a patient with Cushing's disease and gross enlargement of the pituitary.

Transfrontal hypophysectomy was performed in a patient with Cushing's disease and gross enlargement of the pituitary. Despite some reduction of cortisol production active Cushing's syndrome remained due to the presence of a tumour remnant. Medical treatment with the GABA-transaminase inhibitor sodium valproate induced hypocorticism necessitating corticosteroid substitution therapy. Nine months after sodium valproate withdrawal hypercorticism was documented. Re-institution of sodium valproate treatment induced hypocorticism again. As sodium valproate is known to induce a decrease of plasma ACTH in Nelson's syndrome, it is proposed that large tumours present at the time of diagnosis and those appearing after adrenalectomy may represent the spectrum of a single disorder. A prospective trial to study the effects of sodium valproate and other neurotransmitter modulating agents on the size and endocrine function of ACTH secreting macroadenomas is urgently needed.