Usefulness of preoperative inferior petrosal vein sampling in Cushing's disease.

Adrenocorticotropic hormone (ACTH) levels from the inferior petrosal sinuses and peripheral veins were measured in 10 patients with Cushing's disease. All patients had normal or indeterminate computed tomography scans. In 9 of the 10 patients the petrosal vein sampling showed a gradient between pituitary ACTH and peripheral ACTH verifying the supposition of pituitary dependent hypercortisolism. In seven cases preoperative ACTH levels lateralized tumor to one side of the gland. In six of these cases tumor was found at that location at surgery. In the seventh case, no tumor was identified at surgery and that half of the gland was resected. Nine patients were cured following transsphenoidal excision of tumor.