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 - June 2018. PATIENTS: 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=0.028), lower median renin (17.0 vs 27.6 mIU/L, p=0.034), and higher median ARR (20.7 vs 10.3 (pmol/L)/(mIU/L), p=0.001) than males, despite having lower systolic (135 vs 145 mmHg, p=0.021) and diastolic (89 vs 96.5 mmHg, p=0.007) 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=0.005), 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.