ACTH and cortisol response to bromocriptine, and results of long-term therapy, in Cushing's disease.

Plasma corticotrophin (ACTH) was lowered in 4 out of 5 patients with pituitary dependent Cushing's syndrome (one of whom was studied only after bilateral adrenalectomy) after a single oral dose of 2.5 mg bromocriptine, but plasma cortisols were unaltered in the 3 patients in whom it was measured. Three patients were observed during treatment with bromocriptine for 16 to 87 weeks. One improved symptomatically while maintained on a combination of metyrapone and bromocriptine, but plasma ACTH levels remained high even when the dose of bromocriptine was increased to 20 mg daily. Bromocriptine therapy was discontinued after 16 weeks in the second patient due to the development of mental depression. Her clinical features had not improved during this time. The third patient, who also underwent a course of pituitary irradiation, became, and remains, symptom free, with satisfactory plasma ACTH and cortisol levels for the 87 weeks he has received bromocriptine. The role of bromocriptine in the management of Cushing's disease seems limited despite the fact that plasma ACTH may fall after a test dose of the drug.