Salivary cortisol and the diagnosis of Cushing’s syndrome: a coming of age

Abstract

The diagnosis and differential diagnosis of endogenous hypercortisolism—the Cushing’s syndrome—is one of the most challenging problems in clinical endocrinology. Screening the large proportion of the population with one or more of the signs and symptoms of Cushing’s syndrome requires a simple, inexpensive, and reliable test [1]. As has been demonstrated in multiple studies, the measurement of an increased late-night salivary cortisol (LNSC) clearly fits the bill because of its high sensitivity and specificity for the diagnosis of Cushing’s syndrome [2]. The theory behind the test and its execution has been exhaustively reviewed and is now widely accepted [3, 4]. The study by Belaya et al. [5] appearing in this journal confirms prior studies that the measurement of LNSC can be performed by a widely available platform immunoassay. Considering the simplicity of obtaining an LNSC sample and the availability of the measurement by platform immunoassay, there should be no barrier to any clinician obtaining this screening test even with a modest degree of suspicion of Cushing’s syndrome. The study of Belaya et al. brings up a few caveats and issues that should be considered when doing the test.