Long-term effects of losartan on proteinuria and renal function in patients with renal amyloidosis

To investigate the effect of the angiotensin II receptor antagonist losartan on proteinuria in secondary amyloidosis cases.

Sixteen patients with renal biopsy-proven AA amyloidosis with proteinuria were included in the study. All the patients had received colchicine treatment for at least 18 months. The patients were divided into two groups with similar age and gender distributions. Eight patients were given losartan at a dose of 50 mg/day for 12 months and the other 8 patients served as controls. Mean arterial blood pressure, proteinuria, serum albumin level and renal function were determined at the initiation of the study and after 1 and 12 months.

There were no significant differences in proteinuria, serum albumin level, renal function or mean arterial blood pressure at the initiation of the study. In the losartan group daily proteinuria decreased significantly from 5.2 +/- 0.7 g at the initiation of the study to 3.9 +/- 1.2 g at 1 month and 3.6 +/- 0.8 g at 12 months, while in the control group it changed from 4.6 +/- 1.0 g to 4.7 +/- 1.0 g and 6.1 +/- 1.2 g, respectively. The increment at 12 months was significant. After 12 months of treatment with losartan, proteinuria was significantly lower in comparison to the degree of proteinuria in the control group. Serum albumin level increased significantly in the losartan group but was unchanged in the control group. In the control group, creatinine clearance showed a significant decrease. There was no significant difference in mean arterial blood pressure measurements, serum creatinine levels, total protein, albumin and creatinine clearance levels between the two groups.

Losartan seemed to prevent an increase in proteinuria without altering the creatinine clearance level in patients with amyloidosis type AA during a 12-month period. This indicates that losartan may be used to decrease proteinuria in this patient group. However, our results are only preliminary and need to be confirmed by larger studies.