CORRELATION BETWEEN HISTOLOGIC FEATURES AND GLOMERULAR-PERMEABILITY IN MEMBRANOUS NEPHROPATHY AND IMMUNOGLOBULIN-A NEPHROPATHY

We evaluated the correlation between histologic features and glomerula r permselectivity based on fractional clearances of dextrans relative to inulin (FCsDex). The subjects consisted of 12 healthy volunteers, 1 8 patients with membranous nephropathy, and 20 patients with immunoglo bulin A nephropathy. In membranous nephropathy, FCsDex measured with l arge dextrans (radii larger than 56 Angstrom) increased as the capilla ry lesion progressed. Histologic examination showed that glomerular ca pillary alteration was the factor most closely linked to changes in FC sDex in membranous nephropathy. Proteinuria (normalized to glomerular filtration rate) did not correlate with FCsDex. Increased FCsDex tende d to normalize during prednisolone treatment in membranous nephropathy . In immunoglobulin A nephropathy, the impairment of glomerular size s electivity depended on the degree of mesangial sclerosis and tubuloint erstitial injury. FCs of dextrans of 59 Angstrom were correlated with the mesangial sclerosis index (r = 0.573, p = 0.050) and the tubuloint erstitial injury index (r = 0.707, p 0.003). Proteinuria (again normal ized to glomerular filtration rate) was significantly correlated with FCs of large dextrans in immunoglobulin A nephropathy (r = 0.668, p = 0.008). We conclude that glomerular size-selective barriers were impai red both in membranous nephropathy and immunoglobulin A nephropathy. H owever, the mechanisms of impaired size selectivity might differ, at l east in part, between these nephropathies. The predominant factors res ponsible for the size-selective defect seemed to be glomerular capilla ry wall lesions in membranous nephropathy but mesangial sclerosis or t ubulointerstitial damages (or both) in immunoglobulin A nephropathy.