Hypophosphatasia : The importance of alkaline phosphatase in bone mineralization
Somchit Jaruratanasirikul, Assoc. Prof., D. of Pediatrics, F. of Medicine, PSU.
Prasin Chanvitan, Asst. Prof., D. of Pediatrics, F. of Medicine, PSU.
Corresponding e-mail : jsomchit@ratree.psu.ac.th
Published : J Med Assoc Thai 1999, 82(12) : 1268-1272
Key words : alkaline phosphatase, bone mineralization, hypercalcemia, hypophosphatasia
The authors describe a neonate who was diagnosed with "perinatal hypophosphatasia". The clinical manifestations in this patient were small head size, soft calvarium (caput membranaceum),
and short bowing forearms and legs. Laboratory investigations revealed hypercalcemia at 12.7 mg/dl, hyperphosphatemia 8.6 mg/dl, and extremely low alkaline phosphatase 0 unit/L. Roentgenographic studies of the skull showed calcification only at frontal bone and base of skull. Spines were small and flattened. Long bones were hypomineralized and deformed. The functions of alkaline phosphatase
to bone development and mineralization were reviewed. Because perinatal hypophosphatasia is a
fatal condition and inherited as autosomal recessive pattern, prenatal diagnosis is necessary. The most reliable and suitable method in our facility is serial ultrasonography which the diagnosis can be
clearly made by second trimester.
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