Endocrine Abstracts

Introduction: Recent primary aldosteronism (PA) guidelines recommend screening all hypertensive patients using the aldosterone-to-renin ratio (ARR). With a 10–13% prevalence of PA in the hypertensive population, PA case detection and subclassification of patients would overwhelm endocrine services. Surgical outcomes at two years are highly variable with the greatest likelihood of complete clinical success (by PASO criteria) seen in those with the KCNJ5 mutated aldosterone-producing adrenal adenomas (APAs). Early identification of KCNJ5-mutant cases could help select those who will benefit the most for invasive treatments. Plasma hybrid steroid profiling—namely the 18-hydroxycortisol:cortisol ratio—can distinguish KCNJ5-mutant APAs from others. This pilot study evaluated whether salivary hybrid steroid measurement could replicate plasma findings, exploring its potential as a simple, non-invasive screening tool to stratify PA patients early in the diagnostic pathway.

Methods: Early morning and late-night saliva samples collected onto Sarstedt Salivette® collection devices, and venous EDTA plasma samples, were collected from 51 patients who satisfied the Endocrinology Society criteria for diagnosis of PA, 3 non-PA controls were also included. Aldosterone, 18-hydroxycortisol, 18-oxocortisol and cortisol were measured by LC-MS/MS. Paired analysis was conducted between the collection modalities.

Results: Patients with raised concentrations of hybrid steroids in plasma also exhibited raised concentrations in early morning saliva (R-squared 0.70/0.66 for 18-oxocortisol/18-hydroxycortisol respectively). Early morning hybrid steroid concentrations were approximately five-fold higher than the corresponding late-night sample. Correlation of plasma with late-night saliva samples was variable (R-squared 0.37/0.66 for 18-oxocortisol/18-hydroxycortisol respectively).

Discussion: Hybrid steroids in saliva correlate well with those found in plasma in this pilot study, indicating potential for large-scale use in screening the hypertensive population. The comparison of saliva samples taken at two different time points highlights the probable impact of ACTH on the production of hybrid steroids. Further work in demonstrating sensitivity and specificity for KCNJ5 mutant detection is necessary.