Resolution of proximal tubular dysfunction after liver transplantation in ATP8B1 deficiency: A case report.

Progressive familial intrahepatic cholestasis type 1 (PFIC1), caused by ATP8B1 deficiency, is a multisystem disorder with extrahepatic manifestations; however, renal involvement has rarely been described. We report a child with genetically confirmed PFIC1 who underwent living donor liver transplantation (LT) for progressive liver disease. Before transplantation, serum creatinine was normal, but a Fanconi-like proximal tubular dysfunction was characterized by elevated urinary β2-microglobulin, proteinuria, phosphaturia, hypercalciuria, and metabolic acidosis requiring bicarbonate supplementation. Following transplantation, these abnormalities rapidly resolved, supporting the hypothesis of reversible cholestasis-associated tubular injury. This case identifies proximal tubular dysfunction as an underrecognized, potentially reversible manifestation of severe, prolonged cholestasis in PFIC1 and supports systematic evaluation of tubular markers before transplantation.