[A predictive and prognostic study on two cases of transient hyperphosphatasemia of infancy]

We presented two cases with transient hyperphosphatasemia (TH) of infancy, whose serum alkaline phosphatase (EC 3.1.3.1, ALP) activity showed markedly increased and the atypical isoenzyme fractions were seen by electrophoresis. These isoenzymes migrated into normal bone ALP region (alpha 2-beta globulin fraction) and fast liver ALP region (fast alpha 2 globulin fraction). From various investigation such as, heat stability, inhibition test by amino acid, neuraminidase treatment and Triton X-100 treatment, former fraction seemed to derive from bone ALP and later fraction from liver ALP. From our study, increment of the activity of alpha 2-beta gl fraction was in advance one month before maximum ALP activity stage, and fast alpha 2 gl fraction followed increasing 3 weeks after that. On the other hand, decreasing of fast alpha 2 gl fraction showed a shorter delay than alpha 2-beta gl fraction. These results suggest that a differential exchange of sugar chain or an impaired clearance of the enzyme from circulation was possibly occurred. It seemed to be important to increase a study of such a predictive and prognostic change of ALP activity and isoenzyme fraction in TH cases.