Clinicopathologic findings relevant to disappearance or relapse of proteinuria following corticosteroid treatment in IgA nephropathy patients with proteinuria of 0.5 to 2.0g/day

Background. We investigated the clinical and pathological findings relevant to the efficacy of corticosteroid treatment in IgA nephropathy patients with 0.5 to 2.0g/day of proteinuria at the initiation of corticosteroid treatment. Methods. In 27 IgA nephropathy patients who received 2-year prednisolone treatment, we analyzed the differences in clinical and pathological parameters (1) between patients with and without disappearance of proteinuria (less than 0.15g/day), and (2) between patients with and without relapse of proteinuria (more than 0.5g/day) at the end of follow-up. Results. The levels of proteinuria and mesangial proliferation at the initiation of prednisolone treatment were significantly lower in patients with disappearance of proteinuria at the end of follow-up than in those without. The levels of active extraglomerular lesions and tubulointerstitial mononuclear cell infiltration and/or fibrosis, and the activity index, were significantly higher in patients with relapse of proteinuria than in those without. Conclusions. In IgA nephropathy patients with 0.5 to 2.0g/ day of proteinuria, disappearance of proteinuria following 2-year prednisolone treatment can be expected in patients with less proteinuria and less mesangial proliferation at the initiation of the prednisolone treatment. Furthermore, active extraglomerular lesions, the activity index, and tubulointerstitial cell infiltration and/or fibrosis appear to be more suitable risk markers for relapse of proteinuria than the initial levels of proteinuria.