Transient Hyperphosphatasemia in an Adolescent and an Adult Renal Transplant Patient

Abstract

In renal transplant patients receiving immunosuppression, a significant increase in alkaline phosphatase (ALP) might be indicative of liver or bone diseases caused by many factors. In infancy and early childhood, a transient and therefore benign increase in ALP often has been described, usually during a course of infectious disease. Rarely, transient hyperphosphatasemia occurs in adults. We herein present 2 cases of transient hyperphosphatasemia in an adolescent and an adult renal transplant recipient, respectively. In the first case, a 17-year-old adolescent presented with an ALP value up to 2451 U/L, reporting no symptoms. In the second case, a 56-year-old woman with a second well-functioning kidney transplant presented with an ALP value up to 1532 U/L, without symptoms. In both cases, the biochemical profile and ultrasound study were negative for liver disease while no viral or other type of infection was detected. Bone scanning was within normal range and parathyroid hormone was also normal. However, bone ALP was measured at 8.9 and 11.9 times, respectively, above reference values. ALP electrophoresis had a characteristic pattern with involvement of both liver and bone-specific isoforms. About 6 weeks after their peak, ALP values gradually returned to normal range. Benign transient hyperphosphatasemia, although rare, should be considered in the differential diagnosis of isolated ALP increase, even in adult patients with kidney transplant. Electrophoresis of ALP could narrow the diagnostic procedure in cases when neither liver nor bone disease is clinically apparent.