Clinical significance of IgA deposits on the glomerular capillary wall in IgA nephropathy

Abstract

In an attempt to clarify the clinical significance of IgA deposits on the glomerular capillary wall, kidney biopsy specimens obtained from 166 patients with IgA nephropathy were studied. According to the immunofluorescence findings of the renal glomeruli, they were divided into 2 groups. One group consisting of 51 patients (31%) revealed IgA deposits on the capillary wall as well as in the mesangial area (capillary type). The other group of 115 patients (69%) had IgA deposition only in the mesangial area (mesangial type). In the capillary type group, 24 patients (47%) revealed glomerular crescents involving more than 10% of observed glomeruli compared to only 9 patients (8 %) in the measangial type group (p<0.01) . The daily amount of urinary protein excretion prior to the histological examination was 2.0 and 0.7 g, and serum creatinine higher than 1.5mg/dl was marked in 13 (25%) and 3 (3 %) patients, in the respective groups (p<0.01, p<0. 01). Ten of the 12 patients examined in an acute exacerbation, which was indicated by the abrupt appearance of macroscopic hematuria and heavy proteinuria, revealed capillary type IgA deposits (p< 0.01). During a follow-up period ranging from 6 months to 14 years ; with a mean of 3.2 years, renal function declined (serum creatinine > 1.5 mg/dl) in 10 patients (20%) with capillary type and 4 patients (3 %) with mesangial type deposition (p<0. 01). These results disclosed that IgA deposits on the glomerular capillary wall had a close relation to crescent formation, massive proteinuria and decline of renal function, and suggest that the deposits are one of important factors participating in the progression of IgA nepropaty.