Recurrent transient hyperphosphatasemia of infancy in an adult.

We report a case of recurrent transient hyperphosphatasemia in a 29-year-old man with immune deficiency. He had serum alkaline phosphatase (ALP; EC 3.1.3.1) activity 16.9- and 4.8-fold greater than the upper reference limit on two occasions; the activity returned to normal within 2 months on the first and within 1 month on the second. On both occasions we observed the typical electrophoretic pattern for ALP isoenzymes seen in transient hyperphosphatasemia of infancy. We noted no evidence of liver or bone disease. Recognition of the occurrence of transient hyperphosphatasemia of infancy in adults, although rare (it is the fifth case reported), seems as important as in children so that unnecessary extensive investigations are avoided.