Clinical utility of late-night and post-overnight dexamethasone suppression salivary cortisone for the investigation of Cushing's syndrome.
INTRODUCTION
There is a pressing need to identify diagnostic testing for Cushing's syndrome that can be achieved with ease and at low cost. This study aimed to explore the usefulness of late-night and post-overnight 1-mg dexamethasone suppression salivary cortisone, as measured by liquid chromatography-tandem mass spectrometry, for investigation of hypercortisolism.


METHODS
Salivary cortisone data of subjects were investigated according to a pre-specified protocol. Subjects were classified as having 'hypercortisolism' or 'eucortisolism' on the basis of histological or biochemical criteria. Receiver operating characteristic curves were drawn to identify the cut-off values and study their performance characteristics. We measured 24-hour urinary free cortisol; late-night salivary cortisol and cortisone; and post-overnight 1-mg dexamethasone suppression serum cortisol, and salivary cortisol and cortisone. Saliva and urine samples were assayed by liquid chromatography-tandem mass spectrometry.


RESULTS
In this study, 21 subjects were classified as having hypercortisolism and 78 as having eucortisolism. A late-night salivary cortisone cut-off of 13.50 nmol/L had a sensitivity of 94.7% and a specificity of 87.2%. After taking 1-mg dexamethasone the night before, a salivary cortisol cut-off of 0.85 nmol/L had a sensitivity of 76.2% and a specificity of 96.2%; a salivary cortisone cut-off of 7.45 nmol/L had a sensitivity of 85.7% and a specificity of 94.9%, while a salivary cortisone cut-off of 3.25 nmol/L had a sensitivity of 95.2% and a specificity of 79.5%. Many salivary cortisol samples were below the detection limit of liquid chromatography-tandem mass spectrometry. In comparison with salivary cortisol, salivary cortisone had a better correlation with total serum cortisol and better diagnostic performance following dexamethasone suppression.


CONCLUSIONS
Both late-night and post-overnight dexamethasone suppression salivary cortisone levels are of diagnostic value in the investigation of hypercortisolism.
['Ng|C M|CM|', 'Lam|T K|TK|', 'Au Yeung|Y C|YC|', 'Choi|C H|CH|', 'Iu|Y P|YP|', 'Shek|C C|CC|', 'Tiu|S C|SC|']
D000328:Adult D000368:Aged D000369:Aged, 80 and over D000893:Anti-Inflammatory Agents D002853:Chromatography, Liquid D002940:Circadian Rhythm D003348:Cortisone D003480:Cushing Syndrome D003907:Dexamethasone D005260:Female D006801:Humans D006854:Hydrocortisone D008297:Male D008875:Middle Aged D011237:Predictive Value of Tests D012372:ROC Curve D012463:Saliva D012469:Salivary Glands D012680:Sensitivity and Specificity D055815:Young Adult
Dexamethasone Cortisone Cushing syndrome