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November 17, 1993

Loperamide to Diagnose Cushing's Syndrome

JAMA. 1993;270(19):2301-2302. doi:10.1001/jama.1993.03510190055022

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