Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2008) 16 P29

ECE2008 Poster Presentations Adrenal (61 abstracts)

Late night salivary cortisol in the diagnosis of Cushing's syndrome

Jeyaraman Kanakamani , Gupta Nandita & AC Ammini


All India Institute of Mediacl Sciences, New Delhi, India.


Introduction: Late night salivary cortisol appears to be promising as a simple stress-free screening test for Cushing’s syndrome (CS). But there is no consensus on the cut-off value because of the lack of availability larger studies and of standardization of assays. The normal reference ranges are assay-dependent and should be validated for each laboratory.

Objective: The purpose of this study was to evaluate the usefulness of late-night salivary cortisol in the diagnosis of CS.

Methods: We studied 49 normal subjects and 52 patients with suspected hypercortisolism. Salivary cortisol was collected at 0800 h and 2300 h using a commercially-available salivette and measured by an automated chemiluminescence assay. The study was approved by the Institute’s ethical committee.

Results: Out of 52 patients 20 were confirmed to have CS and in the remaining CS was excluded by dexamethasone suppression test. The 2300-h salivary cortisol of patients with CS was significantly higher (1.24±0.86 μg/dl), as compared with patients in whom CS was excluded (0.109±0.076 μg/dl). The 0800-h cortisol was also significantly higher in CS (1.70±1.40 vs 0.240±0.132 μg/dl). The loss of circadian rhythm highlighted by 0800-h to 2300-h cortisol of < 2 was found in 17 of 20 CS patients. The upper limit of the reference range for 2300 h salivary cortisol was calculated nonparametrically as 0.311 μg/dl, from the data on normal subjects. Two of 20 patients with proven CS had 2300-h salivary cortisol less than the calculated upper limit of the reference range, yielding a sensitivity of 90%; one of these 2 patients had intermittent hypercortisolism.

Conclusion: Late-night salivary cortisol measurement is a simple and reliable screening test for Cushing’s syndrome. A cut-off value of 0.311 μg/dl gives a sensitivity of 90% and specificity of 96.8%. Larger studies and wider availability of validated commercial assays are needed before it could be used as first line screening test.

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