Significance of Ultrastructural Electron Dense Deposits on Glomerular Capillary Loops in IgA Nephropathy

ABSTRACT

To evaluate the clinical and histopathological significance of electron dense deposits on capillary in IgA nephropathy, we reviewed and compared the clinical, laboratory, and pathological features of the patients with IgA nephropathy without loop extension of electron dense deposits(Group I, 91 cases) and IgA nephropathy with loop extension(Group II, 17cases) by ultrastructural examination using transmission electron microscope. IgA nephropathy associated with liver disease, Henoch-Schonlein purpura, systemic lupus erythematosus and the other IgA nephropathies associated with systemic diseases were excluded. The results were as follows; 1) There was no significant difference in age distribution. 2) Generalized edema was more common in group II. 3) Nephrotic ranged proteinuria(>3 g/24hr urine) was more prominent in Group II(52.9%) than Group I(8.8%). 4) Among the groups, segmental or mild deposits on the loops were noted in 13 cases, and severe and generalized deposits in 4 cases. Subendothelial deposits were noted in 6 cases, subepithelial deposits in 3 cases, subendothelial with intramembranous deposits in 1 case, subendothelial with subepithelial deposits in 1 case, intramembranous with subepithelial deposits in 2 cases, and subendothelial, subepithelial and intramembranous deposits in 4 cases. 5) The other associated ultrastructural changes of group II were diffuse effacement of foot processes with microvillous transformation, swelling or vacuolar degeneration of podocytes and glomerular endothelium. 6) According to the WHO morphologic criteria, the grade of Group II was significantly higher than Group I. From the above results, it can be concluded that the extension of electron dense deposits along the capillary loops in the cases of IgA nephropathy is highly correlated with proteinuria in the nephrotic ranged. It seems to be a poor prognostic indicator in view of the facts that it correlats with high histopathologic grading.