Purpose of review: It is now clear that subclinical Cushing syndrome is more prevalent than commonly thought, particularly in patients with poorly controlled type 2 diabetes mellitus and obesity. This review highlights the usefulness of late-night salivary cortisol to screen patients with the Cushing phenotype.
Recent findings: Measurement of an elevated late-night salivary cortisol level has a very high sensitivity for even mild Cushing syndrome. Its simplicity makes it the screening test of choice. Furthermore, a suppressed salivary cortisol the morning after low-dose dexamethasone has very high specificity to rule out Cushing syndrome.
Summary: Even a moderate suspicion of endogenous hypercortisolism should be investigated, particularly in patients with any of the features of Cushing syndrome. The widespread availability of the tools to measure late-night salivary cortisol now enable the clinician to perform a simple screening test for Cushing syndrome that will lead to effective treatment of the currently undiagnosed.