The limited role of midnight salivary cortisol levels in the diagnosis of subclinical hypercortisolism in patients with adrenal incidentaloma

Objective: The criteria for defining subclinical hypercortisolism (SH) are debated and a real gold standard test or combination of tests is lacking. Recently, late-night salivary cortisol (MSC) has been described as a sensitive and easy-to-perform marker for diagnosing overt hypercortisolism. No data are available on the role of MSC in the diagnosis of SH. The aim of this study was to evaluate the sensitivity and specificity of MSC levels in the diagnosis of SH in patients with adrenal incidentalomas (AI). Methods: In 103 (females/males, 69/34) patients with AI, MSC levels were studied. One milligram overnight dexamethasone suppression test (DST), urinary-free cortisol (UFC), and ACTH plasma levels were also evaluated. Patients were defined as affected by SH if they showed two of the following criteria: DST>83 nmol/l, ACTH 193 nmol/24 h. Results: No difference in MSC levels in patients with SH (3.1±3.1 nmol/l) compared with patients without SH (2.2±2.8 nmol/l) was observed. In patients with SH, MSC levels were significantly correlated with DST (r=0.4, P