LATE-NIGHT SALIVARY CORTISOL IS UNALTERED IN PATIENTS WITH POLYCYSTIC OVARIAN SYNDROME (PCOS), IRRESPECTIVE OF DISEASE PHENOTYPE, AND IN OBESE WOMEN, IRRESPECTIVE OF THE PRESENCE OF PCOS.

OBJECTIVE: To determine cutoff values of late-night salivary cortisol (LNSC) using an electrochemiluminescent immunoassay and investigate whether the diagnostic performance of the assay is influenced by the presence of obesity or polycystic ovary syndrome (PCOS).

METHODS: A total of 124 subjects comprising 25 patients with Cushing syndrome (CS), 44 with PCOS (22 nonobese and 22 obese), 21 with constitutional obesity (CO), and 34 healthy subjects (HS) were included in the study. Two consecutive LNSC samples were collected from all participants.

RESULTS: The median LNSC levels of patients with CS were significantly higher than LNSC levels of HS, patients with CO, and obese and nonobese patients with PCOS, respectively (P<.01 for all). Healthy subjects, patients with CO, and obese and nonobese patients with PCOS did not differ in terms of median LNSC levels (P>.05 for all). The cutoff values and corresponding sensitivity and specificity were similar between the groups. The comparisons of the area under curve of the first LNSC (0.963; 95% confidence interval [CI], 0.910 to 0.989), second LNSC (0.954; 95% CI, 0.898 to 0.984), and the mean of two consecutive LNSC (mLNSC) values (0.962; 95% CI, 0.909 to 0.989) did not differ significantly (P>.05 for all). A cutoff value for mLNSC of 7.45 nmol/L yielded a sensitivity of 100% and specificity of 87.5% in HS.

CONCLUSION: In conclusion, LNSC is a reliable test with high diagnostic accuracy in both HS and patients with PCOS and obesity.

ABBREVIATIONS: ACTH = adrenocorticotropic hormone AUC = area under the curve BMI = body mass index CO = constitutional obesity CS = Cushing syndrome E2 = estradiol ECLIA = electrochemiluminescent immunoassay FPG = fasting plasma glucose FSH = follicle-stimulating hormone HOMA-IR = homeostasis model assessment of insulin resistance HPA = hypothalamo-pituitary-adrenal HS = healthy subjects IQR = interquartile range LH = luteinizing hormone LNSC = late-night salivary cortisol LR = likelihood ratio mLNSC = mean of two consecutive LNSC samples PCOS = polycystic ovarian syndrome ROC = receiver operating characteristic UFC = urinary free cortisol WHR = waist-to-hip ratio.