Effect of Eplerenone on the Glomerular Filtration Rate (GFR) in Primary Aldosteronism: Sequential Changes in the GFR During Preoperative Eplerenone Treatment to Subsequent Adrenalectomy

OBJECTIVE: Eplerenone (EPL) is a mineralo-corticoid receptor antagonist that is highly selective and has few side effects. This study was conducted to examine whether or not EPL treatment was able to reverse glomerular hyperfiltration, as an indicator of aldosterone renal action, in primary aldosteronism (PA) patients. METHODS: Changes in the estimated glomerular filtration rate (ΔGFR) were examined in 102 PA patients with EPL treatment. Furthermore, the sequential ΔGFR in 40 patients initially treated with EPL followed by adrenalectomy was examined in order to evaluate the extent of the remaining glomerular hyperfiltration in the patients treated with EPL. RESULTS: EPL decreased the GFR at 1 month after treatment. The GFR at baseline was the sole significant predictor for the ΔGFR. Patients initially treated by EPL followed by adrenalectomy showed three different ΔGFR patterns during the treatment, despite having comparable doses of EPL and comparable control of blood pressure and serum potassium levels. The urinary aldosterone excretion was significantly different among these three groups, and the group with no decrease in the GFR after EPL treatment showed greater urinary aldosterone excretion. Glomerular hyperfiltration was completely restored only in 17.5% of our unilateral PA patients after EPL treatment. CONCLUSION: The present study revealed that blockade of aldosterone action by EPL could, at least partially, reverse glomerular hyperfiltration in PA. Whether or not these differential effects on the GFR affect the long-term outcome needs to be investigated, especially in patients with unilateral PA who do not want adrenalectomy and choose the EPL treatment option.