Hypophosphatasia-study on two autopsy cases.

The autopsy findings of two cases of infantile hypophosphatasia are described and compared with those of 16 previously reported cases. Histochemical and biochemical tissue analysis for alkaline phosphatase showed a marked decrease in activity in liver, kidney, and bones. However, intestinal alkaline phosphatase possessed normal or slightly elevated activity. Nephrocalcinosis is a frequent complication and its development depends on hypercalcemia and length of survival of the patient. Electron microscopic findings are illustrated, and a mechanism for the development of nephrocalcinosis is proposed. For the first time, marked elevations of parathyroid hormone was detected. This finding, coupled with the extreme difficulty in locating the parathyroid glands in cases of hypophosphatasia, is enigmatic. Areas for furture investigation are suggested.