OBJECTIVES:

Evaluate the efficacy of alternate day prednisone versus daily fish oil supplements in slowing or preventing the decline in renal function in children, adolescents, and young adults with moderate to severe immunoglobulin A nephropathy.

PROTOCOL OUTLINE: This is randomized, double blind, placebo controlled, multicenter study.

Patients are randomized into one of three treatment arms: placebo, prednisone, or fish oil. The placebo arm is further randomized to receive either fish oil placebo capsules or prednisone placebo tablets.

Arm I: Patients receive placebo tablets or capsules for 2 years. Arm II: Patients receive a tapering regimen of prednisone tablets administered every other day for 2 years in the absence of unacceptable toxicity.

Arm III: Patients receive fish oil capsules daily for 2 years. Patients may also receive enalapril for hypertension. Patients are followed every 3 months for 3 years after treatment.

PROTOCOL ENTRY CRITERIA:

--Disease Characteristics-- Histologically confirmed immunoglobulin A nephropathy (IgAN) Patients must have either: - Persistent severe proteinuria alone (urine Pr/Cr ratio at least 1.0) OR - Moderate proteinuria plus renal biopsy changes indicating risk of progression (glomerulosclerosis or proliferation) --Prior/Concurrent Therapy-- Endocrine therapy: At least 1 month since any prior prednisone No more than 3 months of prior prednisone therapy since renal biopsy Other: At least 1 month since any prior immunosuppressive therapy or fish oils No more than 3 months of prior immunosuppressive therapy or fish oil administration since renal biopsy --Patient Characteristics-- Hepatic: Bilirubin less than 2 times upper limit of normal (ULN) AST less than 2 times ULN No known chronic liver disease Renal: Protein excretion greater than 0.5 g/1.73 m2/24 hours OR Urine protein/creatinine ratio greater than 0.5 on 2 occasions at least 4 weeks apart in the 6 months prior to study Creatinine clearance at least 50 mL/min Other: No systemic lupus erythematosus No Henoch-Schonlein purpura No diabetes mellitus, cataracts, aseptic necrosis of any bone, or other conditions potentially exacerbated by prednisone therapy Not pregnant Adequate contraception required of all fertile patients