Osteomalacia is a bone disease where the bones soften over time. Osteomalacia is caused by a few internal dysfunctions, one of them being hypophosphatasia, a genetic disorder. Under normal circumstances the body allows the bones to harden. In order to do this calcium, vitamin D, phosphorous and certain enzymes are required. Hypophosphatasia is a type of osteomalacia where the bones do not receive enough bone alkaline phosphatase, an enzyme that helps bones harden, according to the University of Washington.
Cause
Hypophosphatasia is caused by a deficiency in the enzyme alkaline phosphatase, as a result of a genetic mutation. The bone form of alkaline phosphatase stops the activity of pyrophosphatase, an enzyme that prevents bone hardening. Pyrophosphatase is an important enzyme because it prevents the body as a whole from hardening into a solid block when exposed to calcium phosphate in the blood. Pyrophosphatase, however, is not advantageous for bone; exposure to pyrophosphatase softens bone. In the case of hypophosphatasia, pyrophosphatase is not stopped by alkaline phosphatase, resulting in bones becoming soft, according to the University of Washington.
Clinical Presentations
There are six clinical presentations of hypophosphatasia, including lethal perinatal, characterized by the low mineralization and softening of bone, leading to stillbirth. Benign perinatal, bowing the long bones of infants; infantile hypophosphatasia causes increased calcium in the urine, increased cranial pressure, soft bones and teeth; childhood hypophosphatasia causes bone deformity, short stature, fractures and bone pain; adult hypophosphatasia presents with bone fractures in the lower extremities and odontohypophosphatasia causes a loss of alveolar bone tissue resulting in soft bones, according to Etienne Mornet Ph.D., and Mark Nunes M.D.
Signs and Symptoms
Signs and symptoms range from severe to mild. Infants can be stillborn, without the bones mineralized and hardened. Children can experience respiratory distress, seizures, soft teeth, increased cranial pressure and too much calcium in the blood that causes kidney stones, weakness and fatigue. Adults can experience fractures in the lower limbs, arthritis and bone pain, notes the University of Washington and Drs. Mornet and Nunes.
Diagnosis
Although there are a variety of hypophosphatemic conditions, all share a common decrease in serum alkaline phosphatase, the enzyme that allows the bones to harden. Sufferers also present with a genetic mutation in the alkaline phosphatase gene, according to Drs. Mornet and Nunes.
Treatment
To treat arthritic symptoms, non-steroidal anti-inflammatory drugs can be used. Surgical procedures to secure bone fractures may be required. As of 2008, clinical trials have begun to assess the effectiveness of enzyme replacement drugs. Genetic counseling is available to determine if you or a family member is a carrier for this genetic disease, notes the University of Maryland Medical Center.
