MicroRNAs (miRNAs) are present in body fluids and may have the potential to serve as disease biomarkers. This study explored the clinical value of miRNAs in serum and urine as biomarkers for idiopathic childhood nephrotic syndrome (NS).

We obtained serum samples from 159 NS children (24 steroid resistant and 135 steroid sensitive), 109 age/sex-matched healthy controls and 44 children with other kidney diseases. Serum miRNAs were analyzed with the TaqMan Low Density Array and then validated with a quantitative reverse-transcription PCR assay with 126 individual samples. Moreover, we collected paired serum samples from 50 patients before and after treatment to determine the value of these miRNAs for condition assessment. In addition, urine samples from these patients were examined for candidate miRNAs.

The concentrations of serum miR-30a-5p, miR-151-3p, miR-150, miR-191, and miR-19b were highly increased in NS children compared with controls (P < 0.0001). The urinary miR-30a-5p concentration was also increased in NS (P = 0.001). The area under the ROC curve and the odds ratio for the combined 5 serum miRNAs were 0.90 (95% CI, 0.86–0.94; P < 0.0001) and 40.7 (95% CI, 6.06–103; P < 0.0001), respectively. Moreover, the concentrations of the 5 serum miRNAs and urinary miR-30a-5p markedly declined with the clinical improvement of the patients.

We determined that 5 distinct serum miRNAs and urinary miR-30a-5p were increased in NS children. These circulating or urinary miRNAs may represent potential diagnostic and prognostic biomarkers for idiopathic pediatric NS.