Effect of corticosteroid therapy on the progression of IgA nephropathy with moderate proteinuria.

Background: In patients with heavy proteinuria, corticosteroid therapy has been shown to have favorable effects on the progression of IgA nephropathy. However, the efficacy of corticosteroids on the progression of IgA nephropathy with moderate proteinuria is still controversial.

Methods: We assessed 45 adult (age, 18-50 years) patients with moderate proteinuria (0.5-2.0 g daily) and preserved renal function, (serum creatinine concentration, < or = 106 micromol/l) who were diagnosed as having primary IgA nephropathy between December 1993 and July 1998. Twenty-three of the patients were treated with corticosteroids (steroid group), and the remaining 22 patients had no steroid treatment (control group). All patients were followed up for more than 3 years.

Results: There were no differences in baseline characteristics between the two groups, except for proteinuria. In the steroid group, urinary protein excretion was significantly higher than that in the control group. During the follow-up period, urinary protein excretion was not changed in the control group. On the other hand, in the steroid group, mean urinary protein excretion decreased significantly. Seven patients in the control group and 2 patients in the steroid group reached the endpoint, which was defined as a 50% increase in serum creatinine concentration from baseline. Renal survival curves were significantly different between the two groups. A second biopsy was performed in 20 patients who received steroid therapy. Mesangial cell proliferation, mesangial matrix increase, and cellular crescents were significantly reduced in the second compared with the first biopsy specimens.

Conclusions: Steroid therapy is effective in reducing the progression of IgA nephropathy with moderate proteinuria.