SELECTIVE BILATERAL BLOOD-SAMPLING FROM THE INFERIOR PETROSAL SINUS IN CUSHINGS-DISEASE - EFFECTS OF CORTICOTROPIN-RELEASING FACTOR AND THYROTROPIN-RELEASING-HORMONE ON PITUITARY SECRETION

We sought to enhance the sensitivity of selective bilateral blood samp ling to determine adrenocorticotropin (ACTH) and prolactin levels in t he inferior petrosal sinus (IPS) by administering two stimulatory agen ts-corticotropin-releasing factor (CRF) and thyrotropin-releasing horm one (TRH). We then determined the ACTH and prolactin levels in the IPS of 10 patients with Cushing's disease. After peripheral administratio n of both CRF and TRH, ACTH levels were significantly higher on the tu mor side in all patients. The prolactin level was significantly higher on the tumor side when CRF or TRH was used to stimulate pituitary sec retion. Postsurgical immunohistochemistry studies revealed production of both ACTH and prolactin in tumor cells, explaining the abnormal sec retion pattern of the pituitary adenoma. The use of CRF and TRH may th erefore improve the reliability of selective blood sampling and tests from the IPS in those cases of Cushing's disease for which noninvasive methods have otherwise failed to clarify the diagnosis.