[Clinico-pathological characteristics and prognosis of IgA nephropathy patients with microalbuminuria and deposition of complement C3].

OBJECTIVE: To analyze the clinical and pathological data and prognosis of IgA nephropathy patients with microalbuminuria and deposition of C3, and to investigate the significance of C3 deposition in IgA nephropathy with microalbuminuria.

METHODS: The clinical and pathological data of 127 IgA nephropathy patients with microalbuminuria confirmed by renal biopsy in the Jining No.1 People's Hospital from January 2009 to January 2015 and minimum 6-month follow-up was reviewed, and patients were divided into positive group (72 cases, 56.7%)and negative group (55 cases, 43.3%) according to the deposition of C3 in the mesangial area of glomeruli. 24 h urine quantitative protein being more than 1 g, or serum creatinine level becoming abnormal or double by renal biopsy was defined as endpoint of follow-up. Renal survival was calculated by Kaplan-Meier survival analysis.

RESULTS: A total of 127 IgA nephropathy patients with microalbuminuria were followed up successfully, with an average follow-up of (49.6±22.7) months. 24 h urine albumin[(261.3±47.4) vs (238.7±51.9) mg, P=0.011], serum creatinine value[98.0(56.4, 118.6) vs 85.7(51.9, 107.8) μmol/L, P=0.003], uric acid value[(384.0±93.7) vs (360.5±88.4) μmol/L, P=0.043] and serum IgA value[(3.36±1.17) vs (3.12±1.05) g/L, P=0.044] were significantly higher in the C3 positive group than those in the negative group, while the serum complement C3 was significantly lower [(0.70±0.42) vs (0.98±0.49) mg, P=0.047]. Pathological changes [Lee's grade Ⅲ and above Ⅲ: 21(16.5%) vs 11(8.7%), P=0.034], glomerular sclerosis or adhesions [29(22.8%) vs 19(15.0%), P=0.047], renal tubular atrophy or interstitial fibrosis [13(10.2%) vs 8(6.3%), P=0.027] and crescent formation [7(5.5%) vs 2(1.6%), P=0.035] in the complement C3 positive group were more severe than those in the negative group. 38 cases of complement C3 positive group and 14 cases of negative group accomplished the study, and Kaplan-Meier survival analysis showed that there was a significant difference in the median survival time between the two groups [(52.6±8.9) vs (66.1±9.7) months, P=0.019].

CONCLUSIONS: The clinical and pathological features in IgA nephropathy patients with microalbuminuria and deposition of complement C3 were more severe than those without complement C3 deposition, and the prognosis was not optimistic. Therefore, early and active intervention treatment should be considered for these patients.