Urinary leukotriene E4 for predicting steroid sensitivity in children with nephrotic syndrome: an observational cohort study.

BACKGROUND: Nephrotic syndrome (NS) is a common pediatric kidney disorder characterized by proteinuria, hypoalbuminemia, and edema. Leukotrienes (LTs), as inflammatory mediators, may contribute to NS pathogenesis and influence treatment response. This study aimed to assess urinary leukotriene E4 (LTE4) levels in children with an initial onset of NS and evaluate their potential as biomarkers for steroid responsiveness. METHODS: In this observational cohort study, 41 children with a first episode of NS and 41 age- and sex-matched healthy controls were enrolled. Patients were classified into steroid-sensitive NS (SSNS; n = 29) and steroid-resistant NS (SRNS; n = 12) groups following initial steroid therapy. Urinary LTE4 levels were measured prior to treatment, using enzyme-linked immunosorbent assay (ELISA). RESULTS: Urinary LTE4 levels were significantly elevated in children with NS compared to controls (p = 0.001). Although urinary LTE4 to urinary creatinine (U cr) ratios were also higher in patients, the difference did not reach statistical significance (p = 0.09). No significant correlations were observed between urinary LTE4 levels and urinary protein excretion or serum albumin. Furthermore, urinary LTE4 levels did not significantly differ between SSNS and SRNS groups. A receiver operating characteristic (ROC) curve analysis showed poor predictive value of urinary LTE4 for steroid responsiveness, with area-under-the-curve (AUC) values near 0.5. CONCLUSIONS: While urinary LTE4 levels are elevated in children with NS, they failed to reliably differentiate between SSNS and SRNS. These findings suggest a limited role for urinary LTE4 as a predictive biomarker of steroid responsiveness in pediatric NS. However, future large-scale studies incorporating both plasma and urinary leukotriene profiles are warranted to validate its role in disease pathogenesis and treatment response.