Rare case of benign transient hyperphosphatasemia in a complicated multiorgan adult transplant patient: Case report and literature review.

Background: Transient hyperphosphatasemia, characterized by isolated highly elevated alkaline phosphatase (ALP) activity in the absence of liver or bone disease, is typically seen in children but rarely in adults. Here we report highly elevated ALP activity in a complicated multiple-organ transplant patient due to benign transient hyperphosphatasemia.

Case Report: A 54-year-old male had a complicated past medical history including a bilateral lung transplant for cystic fibrosis in 2006, colonic resection due to colon cancer in December 2011 and subsequent chemotherapy which ended in June 2022. He also had combined liver and kidney transplant in 2022 at our academic medical center. Post-transplant, he was treated with triple drug immunosuppressant therapy (tacrolimus, mycophenolic acid, and prednisone). Although his alkaline phosphatase (ALP) activity was 83 U/L, it continued to increase three months after combined liver and kidney transplant even though other liver enzymes were mildly elevated but total bilirubin remained within their reference ranges. Flecainide was discontinued but his ALP remained high, peaking at 5904 U/L. Finally, lansoprazole, ergocalciferol (vitamin D2) and vitamin E supplement were discontinued as nonessential medications, and coincidently ALP activity started to decline.

Conclusions: After ruling out all possibilities that may cause elevated ALP, we concluded that this is a rare case of benign transient hyperphosphatasemia in an adult transplant recipient.