Renoprotective effects of mineralocorticoid receptor blockers in patients with proteinuric kidney diseases

Background. Several studies have demonstrated a short-term antiproteinuric effect of mineralocorticoid receptor blockers (MRB) on proteinuric kidney diseases, but no information is available about the long-term persistence (>1 year) of such reduction in proteinuria and the long-term effects of MRB on renal function. Methods. We prospectively studied the effects of adding spironolactone (25 mg/day) to 87 patients who maintained proteinuria higher than 1 g/day in spite of renin-angiotensin system blockade. The mean follow-up was 25 +/- 15 (1-84) months. Results. Estimated glomerular filtration rate (eGFR) showed an acute fall in the first month of treatment (5.1 +/- 9.4 mL/min/1.73 m(2)), but it remained stable thereafter (+0.04 +/- 0.7 mL/min/1.73 m(2)/month), with a significant difference with respect to the eGFR slope during the 12-month pre-treatment period. The initial eGFR fall predicted a more stable course of renal function, the higher the eGFR initial fall, the better the long-term evolution of eGFR. Proteinuria showed an important and sustained reduction since the first month of treatment. At the end of follow-up, it had decreased by 61% (43-77%) with respect to baseline values. The antiproteinuric and renoprotective influence of spironolactone was also observed in diabetic patients and in patients with renal function impairment, although tolerance was poorer among the latter. Conclusions. Spironolactone induces an initial acute fall in eGFR that predicts a later favourable influence on the course of renal function and a remarkable and sustained reduction in proteinuria.