Diagnostic value of salivary cortisol in Cushing´s syndrome

CARDOSO EML, ARREGGER AL, TUMILASCI OR, CONTRERAS LN

San Francisco, CA, USA

Congreso; The Endocrine Society´s 90th Annual Meeting; 2008

The diagnosis of Cushing´s syndrome (CS) depends on the quality and performance of cortisol assays either in plasma, saliva or urine. The aim of this study was to determine the reproducibility and diagnostic value of late night salivary cortisol (SAF23) for CS using a radioimmunoassay technique. In addition, the cut-off values for saliva and serum cortisol after the overnight 1 mg dexamethasone suppression test (dex) were defined. Twenty one patients with confirmed CS were studied. The control group comprised 61 healthy subjects with normal weight and 60 overweight and obese individuals (C). They all had normal urinary cortisol concentrations (£ 90 µg/ 24 h). All subjects collected whole saliva by directly spitting in polypropilene tubes at 23h for SAF23. In order to estimate the intra-class coefficient of correlation (ICC) of SAF 23, 47 subjects (26 C and 21 CS) collected saliva in two non consecutive days. At 8 h after dex, simultaneous saliva and serum samples for cortisol (SAFdex and Fdex, respectively)  were obtained in 51 subjects (34 C and 17 CS).  SAF and F were determined by RIA (1)    and expressed as nM. Results: The ICC of SAF23 was 0.83 in C and 0.89 in CS. SAF23 > 3.8 nM showed a sensitivity (S) and specificity (E) of 100% and 97.5 %, respectively for diagnosing CS. SAFdex significantly correlated with Fdex ( r: 0.61, p < 0.0001). A cut-off value of SAFdex >2.0 nM and F dex > 50 nM detected CS with 100% S and E. SAF23 and SAFdex seem to be good screening tools based on their non invasive nature, remarkable reproducibility and diagnostic performances. 1. Contreras et al. Clin Endocrinol 2004, 61:675-682.