Endocrine Abstracts

Background: Endogenous Cushing’s syndrome (CS) comprises the symptoms and signs associated with prolonged exposition to inappropriately high levels of glucocorticoids produced by adrenal cortex. Epidemiological studies reported an incidence of 0.7–2.4 cases per 1 million inhabitants per year. Late-night salivary cortisol (LNSC) is one of three currently recommended initial screening tests for CS. The advantages of LNSC are nonivasive specimen collection and minimal influence of preanalytical phase of laboratory process. Results strongly correlate with free fraction of plasma cortisol.

Aims: To screen patients with obesity and/or type 2 diabetes mellitus for the presence of endogenous glucocorticoid hypersecretion by using LNSC test. To asses LNSC value with optimal sensitivity/specificity ratio for CS diagnosis.

Subjects and methods: 281 patients with obesity (n=131) and/or type 2 diabetes mellitus (n=150) were investigated. LNSC was measured by ECLIA (Cortisol Elecsys, Roche Diagnostics GmbH). Every patient with LNSC value more than 4.3 nmol/l underwent estimation of urinary free cortisol (two samples), 1 mg overnight dexamethasone supression test (DST), eventually 2 mg/8 mg DST.

Results: Median of LNSC in group of patients without CS was 7.2 nmol/l (95% CI: 6.8–7.5 nmol/l). Autonomous cortisol secretion was found in five patients, in all of them with ACTH-independent form of CS. Values of LNSC in positive subjects were 12.8, 13.4, 11.9, 32.5 respectively 23.3 nmol/l. Calculated from ROC curve, LNSC value of 11.8 nmol/l had optimal sensitivity/specificity ratio (100% sensitivity and 95.6% sensitivity) for diagnosis of CS.

Conclusions: With regard to noninvasive collection and accesibility, LNSC is adequate test for screening of patients with signs and symptoms of endogenous hypercortisolism.