Significance of deposits and abnormalities of the glomerular basement membrane in tissue injury accompanying IgA nephropathy.

The glomerular injuries in 129 cases of IgA nephropathy (IgA-N) were examined ultrastructurally with special reference to the glomerular basement membrane (GBM) deposits and capillary loop abnormalities, and the correlation between these findings and the clinicopathological data was analyzed. The following results were obtained. 1) The degree of daily excretion of urine protein (UP) and creatinine clearance (Ccr) revealed a significant correlation with the degree of mesangial hypercellularities and the frequency of segmental lesions. 2) All sites of GBM deposits, and discontinuity and/or splitting among the GBM abnormalities showed a significant relation to the severity of proliferation and segmental lesions. 3) The GBM deposits, discontinuity and splitting showed a significant relation to the degree of UP and Ccr. We speculate therefore that capillary loop deposits and/or capillary loop discontinuity and splitting could represent histological prognostic factors for an unfavorable outcome in IgA nephropathy.