Transient hyperphosphatasaemia of infancy.

In five patients with benign transient hyperphosphatasaemia (THP), high activities of so-called "atypical" alkaline phosphatase or fragment isoenzymes were detected. One case occurred after rotavirus infection. Incubation with neuraminidase suggested that "atypical" alkaline phosphatase originated from highly glycosylated bone and liver isoenzymes. This may have been due to virus-induced low isoenzyme clearance from serum. The course of isoenzyme activities in THP following rotavirus infection was followed. Determination of atypical alkaline phosphatase may be useful in the diagnosis of THP.