Abstract
In order to clarify the clinical and histological features of IgA nephropathy associated with impaired renal function, 91 patients with IgA nephropathy were studied. Renal biopsy specimens from 91 patients were examined by light and immunofluorescent microscopy, and 84 cases were examined by electron microscopy. At the time of renal biopsy, GFR was normal in 64 patients, and decreased in 27 patients. The patients with proteinuria more than lg/day and those with hypertension had decreased GFR at the time of renal biopsy, compared with those without such findings. The impaired renal function was found in the group of diffuse proliferative glomerulonephritis, compared with the group of other light microscopic findings. The patients with crescents and/or adhesions of glomerular tuft to Bowman's capsule had decreased GFR, compared with the patients without those histological findings. By electron microscopy, attenuation and splitting of the glomerular basement membrane (GBM) were frequently observed. There was tendency that the patients with marked attenuation of GBM had decreased renal function, compared with the patients without the findings. Subepithelial deposits, intramembranous deposits and subendothelial deposits were not rare findings. Those were found in nineteen, seven and five patients, respectively. The patients with subepithelial and/or intramembranous deposits had decreased GFR, compared with those without such findings. The mesangium was widened in some patients by marked increase in matrix containing a large amount of electron dense deposits. Most patients with such findings had decreased renal function. In conclusion, the clinical features associated with impaired renal function were heavy proteinuria and hypertension. The histological features which were associated with decreased renal function were diffuse mesangial proliferation, crescents and/or adhesions, marked attenuation of GBM, subepithelial and/or intramembranous deposits and diffuse mesangial widening by marked increase in matrix containing a large amount of deposits.
