Endocrine Abstracts

Objective: Patients with primary aldosteronism have an increased risk of developing cardiovascular disease. The response to mineralocorticoid receptor antagonists (MRAs) varies among individuals, indicating diverse mineralocorticoid receptor activities in these patients. This study explored the factors linked to the efficacy of blood pressure reduction through MRAs in patients with primary aldosteronism.

Methods: We retrospectively investigated patients with primary aldosteronism who were newly administered MRA and had no changes in other antihypertensive medications during a 6-month treatment period. We assessed age, estimated daily salt intake, body fat percentage, clinic blood pressure, electrolytes in urine, eGFR, HbA1c, plasma renin activity, and plasma aldosterone concentration. The association between the reduction in blood pressure and patient characteristics before and after undergoing treatment with MRAs was examined. The blood pressure-lowering effect of MRAs was defined as the decrease in systolic BP (ΔsBP) divided by the spironolactone-equivalent dose of MRA at 3 and 6 months (ΔsBP 3M and ΔsBP 6M). The MRA dosage was based on the equivalent spironolactone dosage, with 100 mg spironolactone equal to 100 mg eplerenone or 5 mg esaxerenone.

Results: We examined the relationship between the reduction in blood pressure and patient characteristics in a group of 41 patients with primary aldosteronism (24 males, mean age 55±13 years, including 34 patients diagnosed with bilateral primary aldosteronism) before and after undergoing treatment with MRAs. Significant reductions in office blood pressure were observed 3 and 6 months after treatment initiation. Single correlation analyses showed that the urinary chloride-to-potassium ratio displayed the strongest positive association with blood pressure reduction, surpassing plasma aldosterone concentration, plasma renin activity, and urinary sodium-to-potassium ratio, at 3 and 6 months. Multiple correlation analyses revealed a consistent and independent positive correlation between the urinary chloride-to-potassium ratio and blood pressure reduction at 3 and 6 months. The optimal threshold for the urinary chloride-to-potassium ratio with respect to its ability to lower blood pressure, was determined as 3.18. These results imply that the urinary chloride-to-potassium ratio may be independently associated with the effectiveness of blood pressure reduction facilitated by mineralocorticoid receptor antagonists.

Conclusion: The urinary chloride-to-potassium ratio could potentially serve as a valuable predictor of the effectiveness of MRAs and function as an indicator of endogenous mineralocorticoid receptor activity in patients with primary aldosteronism. Further investigation is needed to determine if similar associations exist in essential hypertension.