“…The measurement of late-night salivary cortisol (LNSC) levels in combination with the 1 mg dexamethasone suppression test (DST) and that of urinary free cortisol (UFC) levels have been proposed as the first-line laboratory tests in the diagnosis of Cushing's syndrome (CS) (3). The lack of a circadian rhythm is a peculiar marker of CS (4), so the LNSC test seems to be the best choice to screen for CS because of its noninvasive, stress-free, easy collection in outpatients (1). There is a marked variation between studies in the performance of the LNSC test, reflecting differences in laboratory assays, sample collection, severity of CS, and control groups (2,5,6,7,8,9,10,11,12,13,14).…”