The effects of spironolactone on nephron function in patients with diabetic nephropathy

Increasing evidence suggests that circulating aldosterone per se contributes directly to renal and cardiovascular diseases. We sought to evaluate the effects of a three-month treatment with 25 mg spironolactone, an aldosterone receptor antagonist, on nephron function in 20 type II diabetic patients with persistent microalbuminuria, despite at least six months' use of an ACEi or ARB (combination group), and in eleven type II diabetic patients with persistent microalbuminuria who have never used an ACEi or an ARB (spironolactone group). In the combination group, urinary protein excretion (UPE, p = 0.015), urinary albumin excretion (UAE, p = 0.010), and the urinary albumin to creatinine ratio (ACR, p = 0.007) decreased, and serum potassium (sK(+), p = 0.004) was significantly elevated. ACR (p = 0.016) decreased significantly in the spironolactone group. In 31 patients given spironolactone (all patients group), UPE (p = 0.019), UAE (p = 0.002), and ACR (p = 0.011) decreased, and serum creatinine (sCr, p = 0.025) and sK(+) (p = 0.002) were significantly elevated. Changes in albuminuria showed a positive correlation with changes in GFR (p = 0.002) and a negative correlation with changes in sCr (p = 0.007), and changes in ACR showed a negative correlation with changes in sCr (p = 0.004) in all patient groups. In our study, we observed that spironolactone, both alone and in combination with ACEi/ARB treatment, was well tolerated, and that it slowed down the progression of diabetic nephropathy with a marked antialbuminuric effect. Our results showed that the antialbuminuric effect developed by the decrease of intraglomerular pressure, particularly in patients with persistent microalbuminuria despite long-term ACEi/ARB treatment; adding aldosterone blockers to treatment was beneficial.