Role of renal doppler in children with idiopathic nephrotic syndrome

Background Renal Doppler can measure intrarenal vascular resistance and may help determine the degree of intrarenal damage, as well as predict subsequent kidney function impairment. However, its utility in children with an underlying kidney disease such as nephrotic syndrome has not been widely examined. This work aimed to measure serial renal resistive index (RI) in pediatric patients with idiopathic nephrotic syndrome to assess its predictive value for steroid resistance and disease outcome. Methods This prospective cohort study included 60 patients with idiopathic nephrotic syndrome aged 5 to < 18 years. Renal Doppler was performed on all children, and renal RI was measured at diagnosis, after 1, 3, and 6 months of diagnosis. Results The average interlobar renal RI of the right and left kidneys at diagnosis, during follow-up at 1, 3, and 6 months, was significantly higher in steroid-resistant nephrotic syndrome than in the steroid-sensitive nephrotic syndrome. Meanwhile, the estimated glomerular filtration rate (GFR) was significantly lower in steroid-resistant nephrotic syndrome than in steroid-sensitive nephrotic syndrome after 6 months, with no significant difference at diagnosis, after 1 month, or 3 months. The average interlobar RI at diagnosis can predict steroid resistance at a cutoff > 0.60 with 92.31% sensitivity and 85.32% specificity. Moreover, the average interlobar RI after 3 months of follow-up can predict short disease outcome at a cutoff > 0.63 with 84.62% sensitivity and 82.98% specificity. Conclusions Renal RI might be an effective non-invasive tool for early prediction and risk stratification of steroid resistance in pediatric patients with idiopathic nephrotic syndrome. Its utility lies in supporting earlier clinical decisions rather than replacing established diagnostic methods.