Isolated idiopathic transient hyperphosphatasemia in an adult patient after renal transplantation: a case report

Abstract

Transient hyperphosphatasemia (TH) is characterized by the isolated elevation of serum alkaline phosphatase (ALP) in children. There is no evidence of liver or bone disease and the ALP levels return to normal within 4 months. Few adult cases have been reported. Here, we report the case of TH in a 54-year-old woman, who for 4 years after receiving a renal transplant, was regularly followed up at a renal outpatient clinic. Her underlying disease was chronic glomerulonephritis, for which she was taking immunosuppressive drugs (cyclosporine and mycophenolate mofetil). Routine laboratory analyses revealed that her ALP level had risen to 909 IU/l, which is a seven-fold increase relative to the upper normal limit (35 130 IU/l). The levels of intact parathyroid hormone; the tumor markers CEA, alpha-FP, CA 19-9, and CA 125; and other serum parameters were normal. The patient lacked symptoms, relevant clinical signs, and evidence of acute infection or acute chronic gastrointestinal disease. Lymph node enlargement and malignancy were not detected on a physical examination and ultrasonographic analysis of the abdomen, respectively. A bone scan showed no evidence of bone pathology. ALP isoenzyme analysis by electrophoresis showed patterns similar to those seen in TH of infancy and childhood. The ALP levels of the patient returned spontaneously to 126 IU/l 5 months after diagnosis. While isolated hyperphosphatasemia in renal transplantation patients may be a benign condition, we recommend that such cases be differentially diagnosed from other diseases that can trigger hyperphosphatasemia, including malignancy, infection, bone and liver diseases.