Corticotropin-releasing hormone stimulation test before and after transsphenoidal selective microadenomectomy in 30 patients with Cushing's disease

Thirty patients with ACTH-dependent Cushing's disease were tested with CRH before and 7-10 days and 3-6 months after selective transsphenoidal adenomectomy. In 28 of 30 patients an adenoma was found, and in 22 (79%) clinical and endocrinological remission occurred. Preoperatively, the majority of the patients had basal and CRH-stimulated plasma ACTH levels that were markedly increased compared to those in normal subjects. On the basis of the CRH stimulation test and low dose (2 mg) dexamethasone suppression test results 7-10 days after surgery, these 30 patients were divided into 4 groups. Groups I, II, and III were patients in remission, as defined by undetectable, subnormal, or normal basal plasma ACTH and cortisol levels in addition to sufficient suppression of cortisol (less than 2 micrograms/dL) during the low dose (2 mg) dexamethasone suppression test. Patients in group IV were not in remission. In group I (n = 6), CRH failed to raise undetectable basal ACTH levels in the early postoperative period; however, 3-6 months later plasma ACTH did increase in response to CRH. In group II (n = 11), undetectable or low basal ACTH levels increased after CRH, and the increase was similar to that in normal individuals. In group III (n = 5), basal ACTH levels were normal, and the response to CRH was exaggerated, but all patients responded normally to the dexamethasone suppression test. The CRH-induced ACTH increase in group III was significantly greater (P less than 0.003) than that in normal subjects, but was similar to that in patients not in remission in group IV (n = 6). Three to 6 months later, the ACTH response to CRH in group III was normal. In summary, the CRH test 7-10 days after surgery in patients with Cushing's disease indicated remission when there was no CRH-induced ACTH response or the response was normal (groups I and II). The test failed to predict remission in patients with an exaggerated CRH-induced ACTH response (groups III and IV). However, with regard to group II, the CRH-induced ACTH increase 1 week after selective adenomectomy indirectly supports the concept of CRH deficiency during hypercorticism and thus, in these patients as well as in group I, a pituitary origin of the disease.