Clinical and pathological features of hyperuricemia in children with IgA nephropathy at a single center

Objective To investigate the clinical, pathological features and risk factors of hyperuricemia in children with IgA nephropathy (IgAN). Methods A retrospective study of 269 primary IgAN children diagnosed between January 1, 2006 to December 31, 2017 at the Children Kidney Disease Center, the First Affiliated Hospital of Sun Yat-sen University, was performed in the hyperuricemia group (uric acid＞350 μmol/L) and the normal uric acid group. The clinical and pathological characteristics were analyzed, and the risk factors of hyperuricemia were analyzed by using multivariate logistic regression analysis. Results There were 185 males and 84 females in the 269 IgAN children with age of (9.2±3.1) years old, among whom there were 70 patients (26.0%) accompanied by hyperuricemia. Clinical indicators such as hypertension, urea nitrogen, serum creatinine, blood lipids, urinary protein in hyperuricemia group were higher than those in normal uric acid group (all P＜0.05), while estimated glomerular filtration rate, serum total protein and albumin were less (all P＜0.05). There were 58 patients (23.0%) and 12 patients (70.5%) associated with hyperuricemia among IgAN children with CKD 1-2 and CKD 3-5. The proportion of hyperuricemia in CKD stage 3-5 IgAN children was statistically higher than that in normal uric acid group (P＜0.01). The hyperuricemia group had a higher proportion of Lee IV and V grade, and a lower proportion of the Lee III grade than the normal uric acid group (all P＜0.05). According to the Oxford pathological classification score, there was no significant difference in total scores of renal lesions, glomerular score, and tubulointerstitial score between the two groups (all P＞0.05). According to the Katafuchi semi-quantitative score, there was no significant difference in the total scores of renal lesions, glomeruli, and tubulointerstitial scores (all P＞0.05), while the hyperuricemia group had higher renal vascular scores than the normal uric acid group (P＜0.01). Multivariate logistic regression analysis showed that hypertension (OR=12.596, 95%CI 1.778-89.243, P=0.011), higher total cholesterol (OR=1.192, 95%CI 1.064-1.336, P=0.002), higher urea nitrogen (OR=1.273, 95%CI 1.104-1.468, P=0.001), proteinuria 3+(OR=1.875, 95%CI 1.309-2.684, P=0.001), proteinuria 4+(OR=1.627, 95%CI 1.241-2.134, P＜0.001) and CKD stage 3 (OR=3.355, 95%CI 1.376-8.181, P=0.008) were the risk factors of hyperuricemia in children with IgAN. Conclusions Twenty-six percent IgAN children patients are accompanied by hyperuricemia, and their clinical parameters and pathological changes are more severe than those in normal uric acid group. Hypertension, higher total cholesterol, higher urea nitrogen, proteinuria 3+/4+ and CKD stage 3 are the risk factors of hyperuricemia in children with IgAN.