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 and greater convenience. We here evaluated the utility of these measurements in patients undergoing an overnight dexamethasone suppression test (ONDST).

Methods: Individuals undergoing an ONDST had parallel measurement of serum cortisol and salivary cortisone at 0900 following midnight dexamethasone(1 mg). Salivary cortisone was measured by electrospray positive ion mode liquid chromatography tandem mass spectrometry (1). The threshold for adequate suppression of salivary cortisone was<2.7 nmol/l; serum cortisol was<50nmol/l.

Results: Results for 25 individuals (24% men (median age 53.0) and 76% women (median age 55.6) were analysed. In 40% of individuals an adrenal adenoma was present; in 53% Cushing’s Syndrome was suspected on the basis of clinical features. Serum cortisol failed to suppress <50 nmol/l in 14/25 cases. We found a strong correlation between 0900 salivary cortisone and serum cortisol after 1 mg ONDST (beta coefficient=0.31, [95% CI 1.4-4.9], P=0.001). When performance of post-dexamethasone salivary cortisone (<2.7 nmol/l) alone in relation to suppression of serum cortisol (<50 nmol/l) was analysed, agreement was 72.3% between tests (Cohens Kappa 0.30 P=0.02), with a positive predictive value of 70% of salivary cortisone (using serum cortisol as the standard) and negative predictive value of 100% in relation to ruling out cortisol excess.

Conclusion: We have demonstrated test validity and clinical utility in substitution of salivary cortisone for serum cortisol in the ONDST as a first-line test. 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.Reference: Jones RL et al. J Chromatogr B Analyt Technol Biomed Life Sci. 2012;881-882:42-48. doi:10.1016/j.jchromb.2011.11.036