Urinary Podocalyxin-to-Creatinine Ratio as a Prognostic Biomarker of Renal Function Decline and Proteinuria Progression in Pediatric Chronic Kidney Disease

Background: Podocyte injury leads to the shedding of podocyte-derived molecules into the urine, which may serve as biomarkers of kidney disease. These molecules could be useful for the early detection of glomerular damage and for monitoring the progression of chronic kidney disease (CKD). Methods: A prospective cohort study was conducted in pediatric patients with CKD stages 1–4 treated at a tertiary care hospital between October 2019 and January 2023. Urinary podocalyxin and creatinine were measured at baseline. Renal function was assessed at baseline and at 12 and 24 months of follow-up. Patients were stratified by CKD stage. Changes in glomerular filtration rate (ΔGFR) were calculated, and correlations with baseline podocalyxin were evaluated using Spearman’s test. Multiple linear regression was used to adjust for confounders. Results: A total of 169 patients were included (median age 11 years). Glomerulopathies were the most frequent etiology (40.8%), and stage 1 was the most prevalent. At 12 months, stage 4 CKD patients showed a positive correlation with ΔGFR (r = 0.709, p = 0.003) and a negative correlation with proteinuria (r = −0.864, p < 0.001). At 24 months, a positive correlation was observed with ΔGFR (r = 0.949, p < 0.001), while an inverse association was observed with GFR. Associations varied according to CKD etiology. Conclusions: The podocalyxin-to-creatinine ratio was positively associated with renal function and negatively with proteinuria in stage 4 CKD, but showed no utility in stages 1–3.