Utility of Renal Resistive Index in Children with Nephrotic Syndrome

Abstract

Background: Renal resistive index (RRI) is one of the Doppler parameters that provide information about arterial impedance. While its utility has been explored in chronic kidney disease and obstructive uropathy, its role in glomerular diseases remains less defined. Aim: This study aimed to measure RRI in children (6–18 years) with nephrotic syndrome, both steroid sensitive (SSNS) and steroid resistant (SRNS), currently in remission. Setting and Design: This cross-sectional study was done over 1 year at a tertiary care teaching hospital from March 2017 to March 2018. Methods: Renal Doppler ultrasound was done and RRI was measured at the main renal, arcuate, and interlobar arteries for both the kidneys during disease remission. Detailed information of disease type, biopsy, and therapy was recorded. Baseline biochemical investigations were done to confirm disease remission. Results: Fifty patients (25 each with SSNS and SRNS) were enrolled; the mean age was 12.6 years. The mean RRI at the interlobar and arcuate arteries was elevated in SRNS in all three poles of both the kidneys as compared to the SSNS with a significant difference at midpole (P = 0.04). RRI values were higher in children having focal segmental glomerulosclerosis (FSGS) compared to those with minimal change disease. The percentage of patients having an RRI value >0.6 was significantly higher in those who had received cyclosporine for >2 years as compared to those who received it for <2 years. Conclusions: Doppler RRI values were elevated for patients with SRNS compared to SSNS; changes were significant at the midpole of both kidneys. Children with FSGS and those on calcineurin inhibitors for more than 2 years are more likely to have higher RRI values.