Losartan reduces proteinuria and preserves renal function in hypertensive patients with IgA nephropathy

Background. The objectives of this study were to evaluate the effects of the angiotensin II receptor antagonist losartan on blood pressure (BP), proteinuria, and renal function in hypertensive patients with IgA nephropathy. Method. The study subjects comprised 18 patients with biopsy-proven IgA nephropathy with mild hypertension. Patients were classified into three groups (good/relatively good, relatively poor, poor) according to renal histologic findings and treated once a day with losartan 50mg for 12 months. Changes in BP, proteinuria, renal function, and biochemical parameters were prospectively evaluated before and after the treatment. Results. BP began to fall after 1 month and proteinuria decreased significantly after 9 months of therapy. Glomerular filtration rate (GFR), renal plasma flow (RPF), and filtration fraction (FF) did not change throughout the observation period, There was no significant difference between the three different histologic groups in relation to the effects of losartan on BP, proteinuria, and renal function. We found that in patients with a proteinuria reduction rate of more than 50%, RPF increased and FF decreased significantly. Although it has been reported that losartan has a uric acid lowering effect, this study could not confirm such an effect. Conclusions. Losartan lowers blood pressure and decreases proteinuria in hypertensive patients with IgA nephropathy. These effects appear to be independent of renal histologic findings. This study suggests that the antiproteinuric effect of losartan is primarily mediated by changes in glomerular hemodynamics.