Effect of Age on Aldosterone–Renin Ratio in Screening Primary Aldosteronism

Primary aldosteronism (PA) is the most common endocrine cause of hypertension. The plasma aldosterone-to-renin ratio (ARR) is the most recommended screening tool for PA, but previous studies showed controversy regarding the influence of age on ARR. The aim of the study was to evaluate the impact of age on ARR measured using direct renin concentration (DRC) and its diagnostic value in patients with PA. We retrospectively collected patients with hypertension who attended Xiangya Hospital for PA screening using plasma aldosterone concentration (PAC)/DRC from January 1, 2017 to November 1, 2023. The patients were divided into the groups of PA and essential hypertension (EH) by confirmatory tests. We performed separate correlation analyses of age and DRC, PAC, and ARR, the patients were then further subdivided into four age groups: < 40, 40-49, 50-59, and ≥ 60 years old. Receiver operating characteristic curve and area under the curve (AUC) were used to determine age-specific ARR cutoff values for screening PA. We screened a total of 478 patients, comprising 255 diagnosed with PA (53.35%) and 176 with EH (36.82%). In patients with EH, PAC and DRC decreased with increasing age (p < 0.001, r = -0.34; p < 0.001, r = -0.28), whereas ARR increased with age (p = 0.002, r = 0.22). However, in patients with PA, DRC, PAC, and ARR did not show significant association with age (p = 0.40, 0.54, 0.33). The cutoff values of ARR for screening PA in four groups were 17.49, 20.79, 21.01, and 18.22. The optimal ARR cutoff was 22.52 in the all-ages, with an AUC of 0.948 (95% CI: 0.929, 0.966), sensitivity of 89.4%, and specificity of 85.2%. There was no significant correlation between age and DRC or PAC in patients with PA. Compared to the consensus-recommended cutoff of 37 (pg / mL)/(μIU/mL), a lower ARR cutoff may be more appropriate for screening PA.