ObjectiveThe use of late-night salivary cortisol (LNSalC) for diagnosing subclinical hypercortisolism (SH) is debated. No data are available regarding the role of LNSalC as measured by liquid chromatography–tandem mass spectrometry (LC–MS/MS) in SH diagnosis. The aim of this study was to evaluate the diagnostic accuracy of LNSalC measured by LC–MS/MS in SH.DesignCross-sectional prospective study of outpatients.MethodsIn 70 consecutive patients with adrenal incidentalomas (AI), without signs and symptoms of hypercortisolism, we diagnosed SH in the presence of at least two of the following: cortisol after 1 mg overnight dexamethasone suppression test (1 mg DST) >83 nmol/l, 24-h urinary free cortisol (UFC) >193 nmol/24 h, and morning ACTH <2.2 pmol/l. The LNSalC levels by LC–MS/MS at 2300 h (normal values <2.8 nmol/l) and the presence of hypertension, type 2 diabetes mellitus (T2DM), and osteoporosis (OP) were assessed.ResultsThe increased LNSalC levels (>2.8 nmol/l) had an 83.3% specificity (SP) and a 31.3% sensitivity (SN) for predicting the biochemical diagnosis of SH. The increased LNSalC had an 85.2% SP and a 55.6% SN for predicting the presence of hypertension, T2DM, and OP, while the combination of LNSalC >1.4 nmol/l (cutoff with 100% SN) plus 1 mg DST >50 nmol/l had an 88.9% SN and an 85.2% SP (similar to SH criterion at enrollment).ConclusionsIn AI patients, LNSalC measured by LC–MS/MS appears to be useful in combination with 1 mg DST for diagnosing SH, while it is not useful as a single criterion.
Application of Liquid Chromatography Tandem Mass Spectrometry to Bioanalysis Services -Role of the "GLP (Good Laboratory Practice)-Free" Laboratory-
