The investigators hypothesize that using Losartan would help decrease proteinuria in controlling proteinuria in children with immunoglobulin A nephropathy.

Twenty nine patient with IgA nephropathy with proteinuria (urine protein to creatinine ratio > 0.3 mg/mg) were included in the study. All patients had received losartan treatment for 24 weeks. Changes in blood pressure, proteinuria, renal function, and biochemical parameters were prospectively evaluated before and at 4 weeks and 24 weeks.

Inclusion Criteria:

• Age: 2years or older and younger than 18 years
• Biopsy-proven Ig A Nephropathy
• Estimated GFR ≥ 90mL/min/m^2
• Mean urinary protein-creatinine ratio > 0.3 g/g from three first-morning spot urine collections

Exclusion Criteria:

• hypertension
• under dialysis or organ transplanted
• bilateral renal artery stenosis
• primary hyperaldosteronism
• pregnant