Selectivity index of proteinuria and its relationship with the interstitial change

In order to know the proteinuria selectivity index and its relationship with the interstitial damage 46 patients of different biopsy proven primary glomerulonephrities, (Mesangial prol GN=20, MGN=10, FSGS=8 and MPGN=8) were studied. The selectivity index was measured and the patients were divided in three groups as highly selective (SI ≤ 0.1; n=7). Moderately Selective (SI=0.11-0.2; n=13,) and Nonselective (SI > 0.2; n=26,). The extent of the tubulointerstitial damage were assessed by semiquantitative gradings of histological lesions according to Ridson's (1968) criteria. The tubulointerstitial damage (tubular atrophy, interstitial fibrosis) were compared among the selectivity index groups and the interstitial changes were significantly higher in moderately selective group (P < 0.01*) and very significantly higher in non-selective group (P < 0.004**) than the highly selective groups of patients. Urinary IgG was also significantly higher in non-selective group (P < 0.002**) than highly selective group. The moderately selective and non-selective proteinuric patients had significantly higher interstitial changes-like interstitial fibrosis, tubular atrophy which may influence the long term prognosis of the patients.