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Hypophosphatasia


- Discussion:
- rare form of rickets which is often hereditary (autosomal recessive);
- characterized by reduction in alkaline phosphatase;
- premature loss of teeth is common in children and adults;
- skeletal changes:
- may present in infants, children, or may be delayed until adulthood;
- radiographs show an excessive amount of unmemeralized osteoid tissue (similar to rickets);
- infants:
- hypercalcemia may occur;
- this often needs to be treated w/ calcium chealing agents or renal dialysis;
- functional craniosynostosis may raise intracranial pressure;
- early mortality may be as high as 50%;
- children:
- short sature and frontal bossing is common;
- calcium and phosphate levels are usually normal;
- on radiographs, look for radiolucent tongues extending from the growth plates into the metaphysis;
- adults:
- femoral pseudofractures and chondrocalcinosis is common;
- calcium and phosphate levels are usually normal