Selective Proteinuria Index as a Prognostic Index in IgA Nephropathy

Goo, Young Suck; Kang, Ea Wha; Lee, Sang Cheol; Han, Seung Hyeok; Kyung, Hee Doo; Jung, Jae Hun; Yoon, Soo Young; Choi, So Rae; Roh, Hyun Jung; Park, Hyeong Cheon; Kang, Shin Wook; Choi, Kyu Hun; Han, Dae Suk; Lee, Ho Yung

Abstract

PURPOSE: Proteinuria is the hallmark of glomerular injury and results from alterations in glomerular permeability. The permeability of diseased glomerulus has been estimated by selectivity of proteinuria. Recently, some authors showed a significant relationship between selectivity of proteinuria and tubulointerstial damage. The present study examines the role of protein selectivity as a prognostic marker in patients with IgA nephropathy and its correlation with other prognostic indices. METHODS: The selective proteiuria index of 81 cases with IgA nephropathy diagnosed between 1990 and 2000 were reviewed, and each case was subclassified using the following : highly selective(SPI0.2). The mean age of the patients was 27+/-15 years with a follow-up period of 38+/-24 months. Six patients had highly selective proteinuria, thirty three patients had moderately selective proteinuria, and forty two patients had nonselective proteinuria. RESULTS: 1) A significant relationship was found between the SPI and Haas subclasess(p=0.01). With respect to clinical presentaion, hypertension(0, 4, 11 cases, p<0.05), proteinuria(0.52+/-0.35, 1.85+/-1.55, 2.79+/-2.51 g/day, p<0.05) were significant correlation.2) Chronic renal failure was significantly higher in patients with nonselective proteinuria in comparison with patients with selective proteinuria(p<0.05).3) Markers of renal failure by the Cox proportional hazards model were Cr(Exp(B)=4.2, p<0.001), Ccr (Exp(B)=2.1, p<0.05), SPI(Exp(B)=1.7, p<0.05), hypertension(Exp(B)=1.6, p<0.05). 4) In 28 patients of IgA nephropathy with nephrotic syndrome, 9 patients were moderately selective, 19 patients were nonselective. The response to therapy, evaluated retrospectively, was 67% and 16% in moderate and nonselective proteinuria(p=0.01). CONCLUSION: There is a significant relationship between selectivity of proteinuria and clinical para meters. Moreover, the selectivity of proteinuria has a predictive value on functional outcome.