Diagnostic value of salivary cortisol in Cushing´s syndrome

CARDOSO EML, ARREGGER AL, TUMILASCI OR, CONTRERAS LN

CLINICAL ENDOCRINOLOGY

Año: 2009 vol. 70 p. 516 - 521

0300-0664

Summary Objective: the diagnosis of Cushing´s syndrome (CS) remains a challenge in clinical endocrinology.The aim of this study was to determine the reproducibility and diagnostic value of late night salivary cortisol (SAF23) for CS and its utility along the follow-up of treated patients. In addition, using the same radioimmunoassay reactives, the cut-off values for saliva and serum cortisol, assessed synchronically after the overnight 1 mg dexamethasone suppression test (DST) were defined. Design: twenty one patients with confirmed CS and 121 volunteers (C) were studied.  They all collected 24 hour urine for cortisol (UFC). The same day whole saliva was obtained at 23h for SAF23. The intra-class coefficient of correlation (ICC) of SAF 23 was estimated in 47 subjects (21 CS and 26 C). At 8 h, after DST, simultaneous saliva and serum samples for cortisol (SAFdex and Fdex, respectively) were obtained in 51 subjects (17 CS and 34 C). After specific therapy 18 patients with CS were followed with SAF23 measurements. SAF and F were expressed as nM. Results: The ICC of SAF23 was 0.89 in CS and 0.83 in C. SAF23 > 3.8 nM showed a sensitivity (S) and specificity (E) of 100% and 97.5 %, respectively for diagnosing CS. SAF23 correlated positively with UFC ( r = 0.685; p=0.0001). After DST, SAFdex significantly correlated with Fdex (r = 0.61, p < 0.0001). A cut-off value of SAFdex >2.0 nM and F dex > 50.0 nM detected CS with 100% S and E. After successful surgical therapy, 13 patients with CS had SAF23 levels < 3.8 nM (1.4 ± 0.8 nM). Conclusions: SAF23 and SAFdex seem to be good screening tools based on their non invasive nature, remarkable reproducibility and diagnostic performances.