Neonatal hypophosphatasia with elevated serum parathyroid hormone.

Two cases of neonatal hypophosphatasia are described. In case 1, hypercalcemia developed at 2 1/2 months of age and continued until death at 10 1/2 months of age. Serum calcium levels decreased transiently in response to phosphate supplementation, prednisolone, and calcitonin. Significantly elevated levels of PTH were detected at 2 1/2 months of age. At autopsy, no parathyroid glands were found. In case 2, hypercalcemia was not detected in his course. Elevated level of serum PTH was recorded on the 17th day of life. A post-mortem examination revealed the presence of one normal parathyroid gland.