Transient alkaline hyperphosphatasaemia in an adult: biochemical peculiarities

We report on a 27-year-old healthy female with transient hyperphosphatasaemia of adulthood (it is the eighth case ever recorded). A maximum alkaline phosphatase activity of 1950 U/l, 11-fold the upper reference limit, was measured. The activity normalized within 11 weeks. Electrophoresis revealed the typical pattern for alkaline phosphatase isoenzymes observed in transient hyperphosphatasaemia of infancy: a fast-migrating liver isoenzyme and a bone isoenzyme. Contrary to the findings in transient hyperphosphatasaemia of infancy the liver isoenzyme did not precipitate with wheat-germ lectin whereas the bone isoenzyme partially bound to lectin. Biochemical features of transient hyperphosphatasaemia in an adult may be different from those in infancy. Recognition of an atypical pattern could help avoid unnecessary extensive investigations.