Clinical significance of detection of urine renal injury biomarkers in children with primary nephrotic syndrome

Abstract

Objective To investigate the clinical significance of detection of urine renal injury biomarkers in children with primary nephrotic syndrome (PNS). Methods Seventy-nine children with PNS at the Department of Nephrology, Tianjin Children′s Hospital were enrolled from January to December 2016, who were given sufficient glucocorticoid for 4 weeks.According to the response to glucocorticoid, they were divided into steroid-sensitive nephrotic syndrome (SSNS) group (63 cases) and steroid-resistant nephrotic syndrome (SRNS) group (16 cases), then they were divided into simple type and nephritic type according to diagnostic criteria.Urinary levels of microalbuminuria (MAlb), transferrin (TfR), retinal binding protein (RBP), N-acetyl-β-D-glucosaminidase (NAG), α1-microglobulin (α1-MG) and β2-microglobulin (β2-MG) were measured in the children before and after treatment, and the data were analyzed by the statistical method. Results Before treatment, the levels of RBP, NAG, α1-MG and β2-MG in the SSNS group [0.91(1.80) mg/L, 28.00(31.5) U/L, 8.40(14.2) mg/L, 0.45(0.35) mg/L]were lower than those in SRNS group[3.94(4.82) mg/L, 37.10(18.20) U/L, 11.10(21.42) mg/L, 0.66(1.41) mg/L], and the differences were statistically significant (all P<0.05); After treatment, the MAlb, TfR, RBP, NAG, α1-MG, β2-MG in the SSNS group [14.10(5.60) mg/L, 0.40(1.60) mg/L, 0.26(0.38) mg/L, 7.90(9.10) U/L, 2.00(4.40) mg/L, 0.27(0.35) mg/L] were lower than those before treatment[MAlb: 1 704.00(1 995.60) mg/L, TfR: 142.10(81.90) mg/L] and those after treatment in the SRNS group[557.90(1 857.17) mg/L, 117.40(102.10) mg/L, 4.19(5.15) mg/L, 38.80(32.43) U/L, 10.85(16.60) mg/L, 0.63(0.91) mg/L], and the differences were statistically significant (all P<0.05). However, before and after treatment, except for MAlb[before treatment: 2 258.75(2 028.43) mg/L], the indicators in the SRNS group were not significantly improved.Before treatment, the RBP in the SRNS group was significantly higher than that in the SSNS group in children with simple type PNS, and the RBP, NAG, α1-MG and β2-MG in the SRNS group were significantly higher than those in the SSNS group in children with nephritic type PNS (all P<0.05). According to receiver operating characteristic curve, there were obvious differences in the urinary levels of RBP, NAG and β2-MG, and area under curve(AUC) was 0.858, 0.837 and 0.679, respectively, all of which were <0.9, so the value of diagnosis was not high.Logistic regression analysis was used to identify RBP and NAG as influencing factors and to establish a model.Through the combined detection of these two indicators, the diagnostic value was higher (AUC was 0.956), and when the diagnostic sensitivity was 93.8%, the specificity could reach 82.5%. Conclusions Urinary RBP, NAG, α1-MG and β2-MG can early reflect tubular interstitial impairment in children with PNS, especially SRNS.Combined detection of RBP and NAG has certain value in predicting the efficacy of glucocorticoid. Key words: Primary nephrotic syndrome; Microalbuminuria; Transferrin; Retinal binding protein; N-acetyl-β-D-glucosaminidase; α1-microglobulin; β2-microglobulin