ECE2021 Audio Eposter Presentations Adrenal and Cardiovascular Endocrinology (80 abstracts)
1Hedi Chaker Hospital, Department of Endocrinology, Sfax, Tunisia; 2Habib Bourguiba Hospital, Department of biochemistry, Sfax, Tunisia
Introduction
The thresholds of late night salivary cortisol (LNSC) vary widely among studies due to differences in assay methodologies and in control groups. We aimed to verify the analytical performance of the LNSC by electrochimiluminescence assay (ECLIA) and to establish cut-off values of LNSC for the screening of Cushings syndrome (CS).
Methods
Patients with suspected CS underwent screening tests including LNSC and 1 mg Dexamethasone Suppression Test (DST). Subjects with abnormal response underwent a 2 mg DST, ACTH assessment and complementary radiological explorations. For the analytical evaluation, the study was performed with guidance from the clinical and Laboratory Standard Institute.
Results
A total of 56 patients with mean age 58.1 years and sex ratio 1.15 were finally enrolled. 22 patients from 56 had clinically CS (group A), 7 patients had subclinical CS (groupB) and 8 patients had a pseudo CS (group C). Goup D (n = 19) was composed of non-functioning adenomas. Reference range for LNSC was 1.061.58 ng/ml. LNSC was correlated with nocturnal serum cortisol (r = 0.56, P = 0.004), with serum cortisol after 1 mg DST (r = 0.82, P = 0.04) and after 2 mg DST (r = 0.89, P < 0.001) but not with serum creatinine. BMI was correlated with serum cortisol after 1 mg de DST but not with salivary cortisol. Using a 2.48 ng/ml threshold derived from ROC curve analysis, the sensitivity and specificity of LNSC to identify CS was 84.6% and 69.4% respectively. The intra assay and inter assay coefficients of variation were 9.84% and 10.5% respectively. The detection and quantification limits for salivary cortisol measurement were 0.05 ng/ml and 0.08 ng/ml respectively.
Conclusion
Our data confirm the usefulness of late night salivary cortisol measurement as an initial and simple test for screening for Cushings syndrome, using an automated ECLIA.