EFFECTS OF MINERALOCORTICOID RECEPTOR ANTAGONISTS ON ALDOSTERONE TO RENIN RATIO IN PATIENTS WITH PRIMARY ALDOSTERONISM

Abstract

Objective: Current guidelines recommend to withdraw interfering antihypertensive drugs before to perform a screening test for primary aldosteronism (PA). Recent studies suggested that diagnostic work-up of PA might be performed without withdrawing mineralocorticoid receptor antagonist (MRA) treatment in selected patients, especially when severe hypertension and hypokalemia are difficult to control. We designed a prospective study to evaluate the effects of MRA treatment on aldosterone to renin ratio (ARR) in patients with PA. Design and method: We prospectively recruited 121 patients with confirmed PA and started on canrenone treatment. Eighteen patients were enrolled in a short-term treatment cohort to assess the effects of MRA on aldosterone to renin ratio (ARR) and potassium after 2 and 8 weeks of canrenone therapy. One hundred and two patients were recruited in the long-term treatment cohort to evaluate the effects of canrenone on ARR after 2 to 12 months of MRA therapy. Results: Plasma renin activity and potassium displayed a significant increase, and ARR showed a significant reduction compared with baseline in patients with PA after MRA initiation. These effects were observed both after a short- and a long-term treatment with canrenone, and were progressively more significant after longer periods of therapy and with greater doses of MRA. We demonstrated that canrenone assumption severely impacts on the rate of false-negative screening tests for PA, which raised from 16.7% to 72.5% after 2 weeks and 7–12 months of MRA treatment, respectively. Conclusions: ARR testing for PA screening should not be performed under MRA therapy.