Acute Kidney Injury with Cast Nephropathy Following Creatine Loading in a 17-Year-Old: A Pediatric Case Report

Background: This case highlights a 17-year-old male who developed acute kidney injury (AKI) with cast nephropathy following a six-day high-dose creatine loading regimen. The patient presented with bilateral flank pain, a parallel rise in cystatin C and creatinine, and kidney enlargement on ultrasound despite adequate hydration and the absence of rhabdomyolysis markers. Renal biopsy confirmed cast nephropathy without evidence of light chain disease. Clinical Impact: This case underscores the potential risks of high-dose creatine use in adolescents and highlights the importance of kidney function monitoring in athletes using sports supplements.