Clinicopathologic features of IgA nephropathy patients with different levels of proteinuria

To investigate the clinicopathologic features of IgA nephropathy (IgAN) patients with different levels of proteinuria and its clinical significance. This was a single-center retrospective cohort study. Patients with biopsy-proven primary IgAN were enrolled from January 2006 to December 2011 in The First Affiliated Hospital of Sun Yat-sen University, divided into six groups based on proteinuria at biopsy (≤ 0.30 g/d, 0.31 - 0.50 g/d, 0.51 - 1.00 g/d, 1.01 - 2.00 g/d, 2.01 - 3.00 g/d, and > 3.00 g/d). Demographic and clinicopathologic data were collected and analyzed. 1,413 patients were enrolled in this study, with the median proteinuria being 0.61 g/d (interquartile range 0.30 - 1.29). Patients with proteinuria > 0.50 g/d showed significant differences in their clinicopathologic characteristics with higher prevalence of hypertension, hypoalbuminemia, hyperuricemia, hypercholesterolemia and hypertriglyceridemia, worse renal function, higher proportions of segmental glomerulosclerosis, tubular atrophy/interstitial fibrosis, and interstitial inflammation. Even the patients with proteinuria 0.31 - 0.50 g/d exhibited higher uric acid, lower total serum protein and albumin, higher proportions of crescents, and global glomerulosclerosis. Furthermore, multiple risk factors linear regression analysis has shown that there were significant associations between proteinuria and serum albumin, uric acid, total cholesterol, triglyceride, systolic blood pressure, degrees of segmental glomerulosclerosis, proportions of crescents, and global glomerulosclerosis. Clinicopathologic features were significantly worse in IgAN patients with increasing of proteinuria.