Reference Intervals for Aldosterone, Renin, and the Aldosterone-to-Renin Ratio in the Population-based Study of Health in Pomerania (SHIP-1)

The renin-angiotensin-aldosterone system plays a key role in the regulation of human blood pressure. The aldosterone-to-renin ratio (ARR) is widely accepted for screening the primary hyperaldosteronism (PAL). Various cutoffs for positive PAL screening have been defined in patient cohorts from endocrinological referral centers and primary care. However, the distribution of the ARR in the general population is largely unknown. We aim to provide reference ranges for plasma aldosterone concentration (PAC), plasma renin concentration (PRC), and the ARR for the general population of north-east Germany. A cohort of 3 300 subjects participated in the first follow-up of the longitudinal, population-based Study of Health in Pomerania (SHIP). PAC and PRC were measured by radioimmunometric procedures. The reference interval was defined as the central 95% range between the 2.5(th) and 97.5(th) percentiles. A reference population comprising 1 347 healthy subjects was selected. Sex and age-specific (25-54 and 55-74 years) reference ranges are presented. The upper reference limit for the ARR was 14.2 and 20.3 in younger, and 22.4 and 25.5 in older men and women, respectively. Time of blood sampling had no influence on the ARR, while beta blockers, and agents acting on the renin-angiotensin system were associated with higher and lower ARR, respectively. Our upper reference limit for the ARR is clearly lower than previously reported values from studies of hypertensive patients in primary care or hypertension referral centers. We confirm that PAC and PRC are associated with various factors, including sex, age, intake of estrogen, and various antihypertensive medications.