Loperamide to Diagnose Cushing's Syndrome

Abstract

To the Editor. —We read with great interest the article by Yanovski et al. 1 Yanovski et al report that the dexamethasone— corticotropin-releasing hormone (CRH) test is a useful test to distinguish patients with Cushing's syndrome from those with a pseudo-Cushing's state. In fact, in the experience of Yanovski et al, the evaluation of cortisol levels 15 minutes after CRH injection, performed after the low-dose dexamethasone test, yields 100% sensitivity, specificity, and diagnostic accuracy. Therefore, Yanovski et al recommend its use as a more accurate procedure to distinguish Cushing's syndrome. In recent years, we proposed the use of loperamide hydrochloride for screening patients with suspected hypercortisolism. Loperamide is a drug that acts as an opiate agonist and is able to inhibit corticotropin levels in normal subjects and in patients with Addison's disease, but not in patients with Cushing's syndrome. 2 In fact, the opioidergic control of corticotropin secretion is operating