Importance of dietary salt restriction in primary aldosteronism during treatment with mineralocorticoid receptor antagonists: role of posttreatment plasma renin levels

Objective: The purpose of this study is to measure the estimated dietary salt intake (eU-NaCl) when primary aldosteronism (PA) is treated with mineralocorticoid receptor antagonists (MRAs) and to evaluate whether it is important to reduce salt intake even while on MRA medications. Design and method: The eU-NaCl values were investigated in 26 PA patients who were treated with MRAs at pre-treatment and 6-month treatment. The eU-NaCl was calculated as follows: eU-NaCl (g/day) = 21.98 * {urinary sodium (mmol / L) / * (Body Weight (kg) × 14.89 + Height (cm) × 16.14 - age × 2.043 - 2244.45)}. Results: Data are shown as median {first quartile - third quartile}. Various clinical parameters of 26 PA patients were compared between pre-treatment and 6 months MRA treatment; Systolic blood pressure (138 mmHg {124.5–157.7} vs 125 mmHg {117.8–130.8}, p < 0.01) and diastolic blood pressure (86 mmHg {80.5–95.0} vs 78 mmHg {74.5–86.3}, p = 0.02) were decreased, serum potassium (3.9 mmol/L {3.8–4.3} vs 4.3 mmol/L {4.0–4.6}, p < 0.01) and active renin concentration (ARC) (2.6 pg/mL {1.2–3.8} vs 6.1 pg/mL {3.5–10.3}, p < 0.01) were increased significantly. The eU-NaCl (8.9 g/day {8.0–10.2} vs. 10.0 g/day {7.8–12.0}, p = 0.27) did not change. The correlation between the difference in eU-NaCl (ΔeU-NaCl) and the difference in ARC (ΔARC) before and after MRA treatment showed a significant inverse correlation (r = -0.418, p = 0.03). Furthermore, when the 26 patients were divided into 2 groups of ARC >5 pg/mL and ARC < 5 pg/mL after MRA treatment, ΔeU-NaCl and ΔARC showed no significant correlation in 16 patients with ARC ≧ 5 pg/mL (r = -0.481, p = 0.11), whereas a strong inverse correlation in 10 patients with ARC < 5 pg/mL (r = -0.7599, p = 0.01). Conclusions: The present data indicate that post-MRA treatment ARC of less than 5pg/mL reflects insufficient improvement of salt sensitivity, suggesting the importance of dietary salt restriction even in the presence of MRA treatment.