HYPOPHOSPHATASIA IN ADULTS: CLINICAL CASES AND LITERATURE REVIEW

Abstract

Hypophosphatasia is a rare inborn error of metabolism caused by mutations in the gene encoding tissue-nonspecific isoenzyme of alkaline phosphatase. Inexpressive clinical picture of the disease in adults is often difficult to diagnose. We present two clinical observations: in one case, the patient was treated for a long time with alfacalcidol and calcium supplementation due to misdiagnosis of systemic osteoporosis with pathologic fractures of the vertebras, although at the presentation the patient had a typical for hypophosphatasia decrease of alkaline phosphatase. In another case, a patient with diagnosis of aseptic necrosis of the femoral head had a sharp decrease in alkaline phosphatase levels at presurgical evaluation. In both cases, the diagnosis was confirmed by genetic testing. For patients with aseptic necrosis the confirmation of the diagnosis of hypophosphatasia determines the need for treatment with asfotase alfa in the postoperative period to preserve the stability of the endoprosthesis.