Heterogeneity of prognosis in adult IgA nephropathy, especially with mild proteinuria or mild histological features.

The present study was undertaken to clarify the clinical course and prognosis of adult patients with primary IgA nephropathy (IgAN), especially with mild proteinuria or mild histological alternations. A population of 735 IgAN patients whom we were able to observe for more than two years was examined. A total of 115 patients (15.6%) was on dialysis during the observation period. The overall 5-year renal survival rate was 92.0%. On the other hand, 166 patients (22.6%) were in clinical remission. A group with mild proteinuria included 197 patients (26.8%). Forty-seven patients of this group showed minor glomerular abnormalities, whereas 12 patients with mild proteinuria showed severe mesangial involvement. Three patients with mild proteinuria were on dialysis during the observation period, whose proteinuria was increased during the clinical course. A group with minor glomerular abnormalities included 82 patients (11.2%). Forty-seven patients of this group showed mild proteinuria, of whom 12 patients showed moderate proteinuria. However, three patients with minor glomerular abnormalities who were not on dialysis showed loss of renal function. These results indicated the heterogeneity of the course and prognosis in IgAN. Even if a patient's initial clinical or histological findings are comparatively mild, strict follow-up management is needed.