Reference intervals for plasma renin and aldosterone concentrations in healthy normotensive multi-ethnic Malaysian adults using DiaSorin chemiluminescent immunoassay

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INTRODUCTION Accurate interpretation of plasma renin concentration (PRC) and plasma aldosterone concentration (PAC) requires population-specific reference intervals, which remain scarce in Southeast Asian populations. Manufacturer-derived reference intervals are based predominantly on Western cohorts and may not be directly applicable to regional populations. MATERIALS AND METHODS This cross-sectional study recruited 300 healthy, normotensive, non-obese adults (149 males, 151 females; mean age 34.4 ± 10.7 years) from a multi-ethnic Malaysian cohort in Sarawak to establish reference intervals for PAC and PRC. Strict exclusion criteria were applied to minimize confounding from medications, smoking, obesity, renal dysfunction, and hypokalemia. PAC and PRC were measured under standardized seated morning conditions using the DiaSorin Liaison® XL chemiluminescent immunoassay (CLIA). Reference intervals were derived using the IFCC-recommended non-parametric method, with sex- and age-stratified analyses. RESULTS The reference intervals were 2.13-30.1 ng/dL (2.5th to 97.5th percentile) for PAC (range 1.25-42.30 ng/dL) and 7.4-66.4 μIU/mL (5th to 95th percentile) for PRC (range 1.31-107.80 μIU/mL). Participants aged ≥40 years had significantly lower PAC and PRC than younger participants. On multivariable regression analysis, PAC was independently associated with serum potassium and estimated 24-h urine sodium excretion, whereas PRC was independently associated with age, sex, systolic blood pressure, and estimated 24-h urinary sodium excretion. No significant difference in PAC and PRC was observed across ethnic groups. CONCLUSIONS We report the first platform-specific, sex- and age-stratified reference intervals for PAC and PRC in a healthy Southeast Asian population using the DiaSorin Liaison® XL CLIA platform. The derived intervals differed from manufacturer-provided values, highlighting the importance of locally validated reference data for accurate interpretation of RAAS biomarkers and clinical evaluation of endocrine and hypertensive disorders.