Relative Fat Mass, Body Mass Index, and Insulin Resistance in Hemodialysis Children at Zagazig University Children's Hospital

Background: Children with chronic kidney disease (CKD) are at increased risk of metabolic disturbances, including insulin resistance (IR). Traditional anthropometric measures such as body mass index (BMI) may not accurately reflect true adiposity or metabolic risk in this population. Relative fat mass (RFM) has emerged as a promising alternative for evaluating body composition and metabolic status. This study aimed to investigate the association between insulin resistance and relative fat mass in hemodialysis children evaluate the diagnostic value of RFM compared to BMI. Methods: This cross-sectional study included 80 pediatric patients on regular hemodialysis for at least 6 months before the study, aged 6–18 years, treated at the pediatric nephrology unit of Zagazig University Hospitals. RFM was calculated using height and waist circumference, and participants were stratified into three RFM categories. Results: The area under the ROC curve (AUC) for RFM was 0.803 (95% CI: 0.70–0.89, p < 0.001), indicating strong diagnostic accuracy. The optimal cutoff value of RFM (≥33.15%) achieved a sensitivity of 75.6% specificity of 80%, with a positive predictive value of 82.9% a negative predictive value of 71.8%, yielding an overall accuracy of 77.5%. In contrast, BMI performed less effectively, with an AUC of 0.62 (95% CI: 0.50–0.73), lower sensitivity (26.7% when using obesity as a cutoff), but comparable specificity (85.7%). Conclusion: RFM provides a more accurate, non-invasive tool than BMI for identifying insulin resistance in pediatric CKD patients. Incorporating RFM into routine clinical practice may improve risk stratification support earlier intervention to prevent adverse metabolic cardiovascular outcomes