Antihypertensive effects and changes in extracellular water content by mineralocorticoid receptor antagonists in patients with primary aldosteronism

In primary aldosteronism (PA), non-suppressible excessive aldosterone secretion due to dietary salt intake significantly contributes to hypertension and cardiovascular complications. Blocking the overactivation of mineralocorticoid receptors (MRs) with mineralocorticoid receptor antagonists (MRAs) is a cornerstone for the medical treatment of PA. However, the role of MRAs in controlling hypertension remains unclear. This study aimed to explore the relationship between changes in body composition parameters (determined by bioelectrical impedance analysis), blood pressure (BP) levels, serum potassium (K⁺) levels and Study 36-Item Short-Form Health Survey (SF-36) scores after MRA treatment in 50 patients with PA. Treatment with MRAs significantly decreased the systolic BP (SBP) and diastolic BP (DBP) levels and extracellular water (ECW) volume, while it increased the serum K⁺ levels, active renin concentrations (ARCs), and scores on several SF-36-based quality of life (QOL) subscales. ECW change (ΔECW) and serum K⁺ change were not significantly associated with changes in SBP and DBP levels. ΔECW showed a significant inverse correlation with ΔARC, suggesting that ARC increases with decreasing ECW volume due to renal MR activity blockade and that ARC is a highly sensitive indicator of ECW volume. In the stratified analysis of patients with PA, ECW volume was significantly decreased in those aged ≥60 years and those with a body mass index of ≥25 kg/m². In conclusion, MRA treatment showed antihypertensive, biochemical, and QOL improvement effects in patients with PA. The antihypertensive effect may not be related to the decrease in ECW volume due to renal MR activity blockade. Evaluation of ECW using BIA in patients with PA treated with MRAs. Abbreviations: ARC, active renin concentration; BIA, bioelectrical impedance analysis; BMI, body mass index; BP, blood pressure; ECW, extracellular water; K⁺, serum potassium; MRA, mineralocorticoid receptor antagonist; PA, primary aldosteronism; QOL; quality of life; Δ, parameter changes after MRA treatment.