[The thinning of the glomerular basal membrane in IgA glomerulonephritis].

Ultrastructural changes of the glomerular basement membrane (GBM) in 34 patients with IgA nephritis and their possible correlation with the main clinical symptoms were examined. In 23 patients thinner than normal GBM segments were found with a mean thickness of 116-120 nm (measured by the method of Osawa). Often foot process fusion but neither disruption nor deposition of immune complexes was seen in the affected capillaries. All patients had hematuria, while those with thin GBM segments had more severe hematuria and more episodes of macrohematuria. Other clinical features were unrelated to ultrastructural changes. It is suggested that the thin GBM may be a predisposing factor to hematuria.