Plasma Renin and Aldosterone Levels in Resistant Hypertension-A Cross-sectional Study in Bangladesh

Abstract

Resistant hypertension (RH) is a challenging clinical condition characterized by persistently elevated blood pressure despite treatment with at least three antihypertensive medications, including a diuretic. It represents a significant public health concern due to its association with increased cardiovascular morbidity and mortality. The renin-angiotensin-aldosterone system (RAAS) plays a pivotal role in the pathophysiology of RH, with abnormalities in plasma renin activity (PRA) and aldosterone levels contributing to sustained hypertension. Understanding RAAS profiles in RH patients can guide therapeutic strategies and improve clinical outcomes. This study aimed to evaluate PRA, plasma aldosterone concentrations, and the aldosterone-to-renin ratio (ARR) in 100 Bangladeshi patients with RH and to explore their clinical implications. A cross-sectional observational study was conducted at the Department of Laboratory Medicine, Department of Biochemistry and Molecular Biology and Department of Cardiology, Bangladesh Medical University, Dhaka, Bangladesh over a period of 1 year from July 2023 to June 2024. Patients aged 18–65 years diagnosed with RH were included. Exclusion criteria encompassed secondary causes of hypertension such as pheochromocytoma, renal artery stenosis, and primary aldosteronism due to adrenal adenoma. Demographic and clinical data, including age, sex, duration of hypertension, comorbidities, and current antihypertensive therapy, were collected. Blood samples were obtained in the morning following overnight fasting, and PRA and plasma aldosterone concentrations were measured using Chemiluminescence immunoassay. ARR was calculated by dividing plasma aldosterone by PRA. The study had a mean age of 58.4 ± 10.2 years, with males comprising 65% of participants. The mean duration of hypertension was 12.5 ± 6.3 years. Comorbidities included diabetes mellitus (45%), chronic kidney disease (30%), and dyslipidemia (40%). The mean PRA was 4.2 ± 3.1 ng/mL/h, and the mean plasma aldosterone level was 238.7 ± 152.3 pg/mL, resulting in a mean ARR of 11.1 ± 8.3. A significant positive correlation between PRA and aldosterone levels was observed (r = 0.68, p < 0.001). Subgroup analysis based on ARR revealed that 60% of patients had low ARR (<10), 25% had intermediate ARR (10–20), and 15% had high ARR (>20). Patients with high ARR exhibited significantly elevated aldosterone levels compared to the low ARR group. These findings demonstrate the heterogeneity of RAAS activation in Bangladeshi patients with RH and highlight the importance of assessing PRA, plasma aldosterone, and ARR for individualized management strategies. Further multicenter and longitudinal studies are warranted to validate these findings and explore targeted RAAS-modulating therapies in resistant hypertension.