BACKGROUND: When mineralocorticoid receptor antagonist therapy is initiated for primary aldosteronism, the response of plasma renin activity indicates the level of cardiovascular risk. The purpose of this article was to compare the effect of mineralocorticoid receptor blockers on plasma renin activity levels in a patient with primary aldosteronism.

CASE REPORT: The patient was a 45-year-old male with severe hypertension. Because his aldosterone/renin ratio was high and a saline infusion test was positive, primary aldosteronism was diagnosed. Computed tomography revealed a low-density mass measuring 10 mm in the left adrenal gland. Segmental adrenal vein sampling demonstrated bilateral primary aldosteronism, so pharmacotherapy was started. Before treatment, his plasma renin activity was 0.5 ng/mL/hour. Eplerenone was commenced and the dose was increased to 100 mg/day. However, his plasma renin activity was still 0.8 ng/mL/hour and the maximum dose of eplerenone did not elevate plasma renin activity above 1 ng/mL/hour. Since plasma renin activity remained below 1 ng/mL/hour with mineralocorticoid receptor antagonist therapy, this patient was considered to have a higher cardiovascular risk than patients with essential hypertension. Accordingly, eplerenone was switched to esaxerenone, a new generation mineralocorticoid receptor blocker that became available in May 2019. After switching to esaxerenone (5 mg/day), the patient’s plasma renin activity increased to 1.8 ng/mL/hour and subsequently remained at 1 ng/mL/hour or higher.

CONCLUSIONS: This is the first case report to present interesting changes of plasma renin activity in a primary aldosteronism patient after switching from eplerenone to esaxerenone. Elevation of plasma renin activity by esaxerenone in our primary aldosteronism patient reflected a mineralocorticoid receptor antagonistic effect that may have alleviated excessive mineralocorticoid receptor activation and volume expansion.

Keywords: Hyperaldosteronism, Hypertension, Mineralocorticoid Receptor Antagonists, Renin-Angiotensin System, eplerenone, Pyrroles, Renin, Sulfones