Transient hyperphosphatasemia following pediatric liver transplantation in a patient with hepatic and skeletal abnormalities

Background: We report a unique case of transient hyperphosphatasemia in a pediatric patient with a history of hepatic and skeletal abnormalities. Patient and Methods: A 2-month old male was diagnosed with progressive familial intrahepatic cholestasis type-2 and osteoporosis after marked increases in liver function tests were noted at 1 month of age. He underwent a second liver transplantation at 1 y. The increased liver function test trend resolved a few weeks post-transplantation. Four months after successful liver transplantation, unexplained significant increases in alkaline phosphatase (ALP) were observed, and they persisted for almost 9 months. Among the etiologies under consideration for the isolated increased ALP activity were viral infections and macro-ALP. Results: A persistent trend in abnormally increased ALP for 9 months was investigated leading to a confirmed diagnosis of transient hyperphosphatasemia (TH). Conclusion: Pediatric post-liver transplant patients with skeletal and hepatic abnormalities including isolated markedly increased ALP activities represent a previously undescribed TH patient population. The 4.3% prevalence of TH in pediatric liver transplant recipients within our healthcare system is considerably higher than the previously reported prevalence of 2.1% for patients within the United States.