Immunoglobulin A glomerulonephritis: a clinicopathologic study.

Renal biopsies from 10 patients staining predominantly for immunoglobulin A are reviewed. Historically, nine of 10 patients were less than 32 years of age; they all presented with either microscopic or gross hematuria. The initial creatinine clearances demonstrated good function in all patients; only one patient experienced a progressive decline in the creatinine clearance. Similarly, proteinuria was mild. The light and electron microscopic findings presented a variable pattern, including a group with changes confined to the mesangium, another group also having glomerular basement membrane changes, and one patient with severe, progressive glomerular sclerosis. Immunogluorescence demonstrated large amounts of IgA predominantly within the mesangium but occasionally involving the peripheral capillary loops. Serum IgA levels were elevated in six of eight patients tested, and two of five patients had elevated nasal IgA concentrations. These data suggest that there is an immunologic entity, IgA glomerulonephritis, characterized by the above clincial findings in association with elevated serum and occasionally nasal IgA levels, but that the pathologic findings are highly variable. Neither the mechanism nor the particular pathogenetic significance of the raised IgA levels is presently known. The similarities of this entity to the reported findings in anaphylactoid purpura are mentioned.