Diffuse form of idiopathic IgA nephropathy (IgAN). A quantitative study.

Fifteen renal biopsy specimens from patients with idiopathic diffuse IgAN for whom both light and electron microscopy as well as immunofluorescence microscopy and full clinical data were available were quantitatively examined and compared with fifteen cases of normal controls. Morphometric investigations were performed by means of a computer image analysis system to evaluate whether morphometric analysis may be helpful in morphologic diagnosis of IgAN and to study whether serum creatinine and changes in quantitatively analyzed glomeruli could correlate with the interstitial fibrosis. The study revealed that total glomerular area, total number of glomerular cells per total glomerular area, and total glomerular cells per unit of glomerular area as well as relative interstitial volume were increased in IgAN in comparison with normal glomeruli, most of them significantly. Moreover, there were significant positive correlations between the width of the cortical interstitium and serum creatinine level as well as between the width of the cortical interstitium and glomerular changes. Although these findings suggest that in IgAN both glomerular and interstitial lesions are involved in the renal prognosis, the authors conclude that a morphometric analysis does not lend itself to establish such causal associations. It was noted that morphometric methods supported by image analysis system cannot be used instead of light microscopy, electron microscopy, and immunohistochemistry, but they can be helpful in precise evaluation of both glomerular and interstitial lesions, which are commonly known as histologic risk factors in primary glomerular diseases.