Endocrine Abstracts

Introduction: Saliva hormone measurements are increasingly being applied in every day clinical practice. In relation to salivary cortisol/cortisone measurement there is a particular advantage, with minimal chance of cross reaction with prescribed glucocorticoids. We here evaluated the utility of these measurements in patients undergoing an overnight (1 mg) dexamethasone suppression test (ONDST).

Methods: A service evaluation of salivary cortisol/cortisone in vs serum cortisol in ONSDT was undertaken. Patients underwent ONDST, with parallel measurement of serum cortisol and salivary cortisone, by electrospray positive ion mode liquid chromatography tandem mass spectrometry. The cut point for adequate suppression of salivary cortisone was<2.7 nmol/l; serum cortisol was <60 nmol/l.

Results: Results for 32 individuals (23% men (median age 62) and 77% women (median age 59) were analysed. In 40% of individuals an adrenal adenoma was present; in 53% Cushings Syndrome was suspected. Serum cortisol failed to suppress in 50% of cases: 8 definite and 8 indeterminate. We found a strong correlation between 0900 salivary cortisone and serum cortisol after 1 mg ONDST beta=29.2 (95%CI 8.91, 49.7) P = 0.008. Performance of post-dexamethasone salivary cortisone (<2.7 nmol/l) alone in relation to suppression of serum cortisol (<60 nmol/l) was analysed. Concordance was 100% between tests: Cohens Kappa 1.0 P < 0.0001. For both tests a definite Cushings Syndrome diagnosis the concordance was 75% Kappa =0.5 P = 0.01. The sensitivity of both tests for Cushings was 100% with a positive predictive value of 50%.

Conclusion: We have demonstrated test reliability and clinical utility in substitution of salivary cortisone for serum cortisol in the ONDST (post-midnight Dexamethasone). Salivary cortisone could therefore be used as an alternative sampling method which does not require venepuncture or attendance at hospital. Application of the test has the potential for significant savings of money and time.