Age- and sex-specific reference ranges are needed for the aldosterone/renin ratio

Objective Current Endocrine Society Clinical Practice Guidelines use a specific aldosterone/renin ratio (ARR) threshold to screen for primary aldosteronism (a treatable disease causing up to 15% of hypertension in primary care) in all patients. We sought to characterize demographic variations in the ARR, hypothesizing a need for age- and sex-specific reference ranges to improve the accuracy of the test. Design Retrospective cross-sectional analysis of ARR measurements at a single tertiary hospital from December 2016 to June 2018. Patients A total of 442 patients with clinically indicated ARR were included, after excluding those who were on spironolactone or the oral contraceptive pill, were pregnant or had an existing adrenal condition. Measurements Aldosterone, renin and the ARR. Results Among those aged 20-39 years (n = 74), females had significantly higher median aldosterone (369 vs 244 pmol/L, P = .028), lower median renin (17.0 vs 27.6 mIU/L, P = .034) and higher median ARR (20.7 vs 10.3 (pmol/L)/(mIU/L), P = .001) than males, despite having lower systolic (135 vs 145 mmHg, P = .021) and diastolic (89 vs 96.5 mmHg, P = .007) blood pressure. The >= 60-year age group (n = 157) also had significant sex differences in the ARR. With increasing age (20-39 vs >= 60 years), there was a significant fall in plasma aldosterone in females (369 pmol/L vs 264 pmol/L, P = .005), with no change observed in males. Conclusions For those 20-39 years old, aldosterone and the ARR are significantly higher in females despite a lower systolic and diastolic BP, highlighting the potential for false-positive results. Our findings indicate the need for prospective studies with a control population to define age- and sex-specific ARR reference ranges.