We herein present the case of a 53-year-old patient with adrenocorticotropin-independent macronodular adrenocortical hyperplasia (AIMAH), which is a rare form of Cushing syndrome. He had hypercortisolemia and bilateral macronodular adrenal glands with a left side predominance. The administration of vasopressin significantly increased the plasma cortisol level (1.9-fold). Following left adrenalectomy, the patient's hypercortisolemia significantly improved and vasopressin responsiveness was lost, suggesting that the responsiveness originated from the resected left adrenal gland. The marked difference in vasopressin responsiveness between the adrenals corresponded with their asymmetrical size and function. Evaluating the differences in the vasopressin sensitivity may therefore be helpful for understanding the progression of AIMAH.
2013 by The Japanese Society of Internal Medicine