CORTICOTROPIN-RELEASING HORMONE TEST - IMPROVEMENT OF THE DIAGNOSTIC-ACCURACY OF SIMULTANEOUS AND BILATERAL INFERIOR PETROSAL SINUS SAMPLING IN PATIENTS WITH CUSHING SYNDROME

Twenty-six consecutive patients with ACTH-dependent Gushing syndrome w ere subjected to simultaneous, bilateral inferior petrosal sinus sampl ing for ACTH assay before and after ACTH-releasing hormone (CRH) stimu lation. The baseline ACTH inferior petrosal sinus/periphery (IPS/P) ra tio was greater than or equal to 2 in 12 of 26 patients (46%), whereas the CRH-stimulated IPS/P ratio was greater than or equal to 3 in 19 o f 26 patients (73%), A pituitary adenoma, ACTH-secreting at immunostai ning, was surgically proved in all of the 19 patients who had an ACTH IPS/P ratio greater than or equal to 2 basally or greater than or equa l to 3 after the CRH test but also in three other patients who did not have such ratios, The value of the basal IPS/P ratio and the complete lack of ACTH increase after CRH led to the diagnosis of an ectopic AC TH syndrome in four patients: a bronchial carcinoid was found in three patients, and the site of the tumor was still unknown in the other. I n conclusion, the CRH test improved the diagnostic accuracy of inferio r petrosal sinus sampling from 61.5% (12 pituitary, 4 ectopic) to 92.0 % (19 pituitary, 4 ectopic). Thus it should be performed during the di agnostic process.