Hypophosphatasia

The signs and symptoms of hypophosphatasia vary widely and can appear anywhere from before birth to adulthood. The most severe forms of the disorder tend to occur before birth and in early infancy. Hypophosphatasia weakens and softens the bones, causing skeletal abnormalities similar to another childhood bone disorder called rickets. Affected infants are born with short limbs, an abnormally shaped chest, and soft skull bones. Additional complications in infancy include poor feeding and a failure to gain weight, respiratory problems, and high levels of calcium in the blood (hypercalcemia), which can lead to recurrent vomiting and kidney problems. These complications are life-threatening in some cases.^[1]

The forms of hypophosphatasia that appear in childhood or adulthood are typically less severe than those that appear in infancy. Early loss of primary (baby) teeth is one of the first signs of the condition in children. Affected children may have short stature with bowed legs or knock knees, enlarged wrist and ankle joints, and an abnormal skull shape. Adult forms of hypophosphatasia are characterized by a softening of the bones known as osteomalacia. In adults, recurrent fractures in the foot and thigh bones can lead to chronic pain. Affected adults may lose their secondary (adult) teeth prematurely and are at increased risk for joint pain and inflammation.^[1]

The mildest form of this condition, called odontohypophosphatasia, only affects the teeth. People with this disorder typically experience abnormal tooth development and premature tooth loss, but do not have the skeletal abnormalities seen in other forms of hypophosphatasia.^[1]

Until recently, management of hypophosphatasia (HPP) has mostly been aimed at addressing symptoms of the condition.^[2] For example:

• Hydration, restriction of dietary calcium, vitamin D, and sometimes thiazide diuretics for hypercalcemia
• Ventilatory support for severely affected infants, some of which need a tracheostomy, which can lead to problems with speech and language development and tolerance of oral feeds
• Physiotherapy, occupational therapy and chronic pain management for pain and motor difficulty
• Surgery for fractures that fail to heal

More recently, research has shown positive effects of human recombinant enzyme replacement therapy (ERT), called asfotase alfa, on people who began having symptoms before 6 months of age. There reportedly have been significant improvements in the X-ray appearances of bone tissue, along with improvements in growth, respiratory function, motor development and calcium homeostasis after 6–12 months of treatment. The children in the original study have now received more than three years of treatment, without apparent major side effects, and with continuing improvement in affected systems.^[2] Asfotase alfa appears to be a valuable emerging therapy for the treatment of bone manifestations in people with pediatric-onset HPP.^[3] In October of 2015 the FDA approved asfotase alfa, sold as Strensiq.^[4]

Bone marrow and stem cell transplantation in infancy and childhood have improved the severity of the disease, but have not provided long term improvement.^[2]

Having hypophosphatasia as a confirmed diagnosis may help patients avoid therapies for osteoporosis or osteomalacia that could be either ineffective or possibly harmful to them.^[5] To learn more about a potential treatment which has shown success for individuals with hypophosphatasia and reduced bone density, click here.

You can find relevant journal articles on treatment of hypophosphatasia through a service called PubMed, a searchable database of medical literature. Information on finding an article and its title, authors, and publishing details is listed here. Some articles are available as a complete document, while information on other studies is available as a summary abstract. To obtain the full article, contact a medical/university library (or your local library for interlibrary loan), or order it online using the following link. Using "hypophosphatasia AND treatment" as your search term should locate articles. To narrow your search, click on the “Limits” tab under the search box and specify your criteria for locating more relevant articles. Click here to view a search.

The National Library of Medicine (NLM) Web site has a page for locating libraries in your area that can provide direct access to journals (print or online) or where you can get articles through interlibrary loan and Loansome Doc (an NLM document-ordering service). You can access this page at the following link. You can also contact the NLM toll-free at 888-346-3656 to locate libraries in your area.
http://nnlm.gov/members/

To learn more about traditional therapies for osteoporosis you can visit the following link from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS): which sponsors the NIH Osteoporosis and Related Bone Diseases ~ National Resource Center. http://www.niams.nih.gov/Health_Info/Bone/Osteoporosis/Medicine/default.asp

The Osteoporosis and Related Bone Diseases ~ National Resource Center, a part of the U.S. Department of Health and Human Services' National Institutes of Health (NIH), provides patients, health professionals, and the public with an important link to resources and information on metabolic bone diseases, including osteoporosis and hypophosphatasia.

NIH Osteoporosis and Related Bone Diseases ~ National Resource Center
National Institute of Health
2 AMS Circle
Bethesda, MD 20892-3676
Toll-free: 800-624-2663
Phone: 202-223-0344
TTY: 202-466-4315
Fax: 202-293-2356
E-mail: NIAMSBoneInfo@mail.nih.gov
Web site: http://www.osteo.org

More information on osteoporosis can be found at the following link from MedlinePlus, the National Library of Medicine Web site designed to help you research your health questions.
http://www.nlm.nih.gov/medlineplus/osteoporosis.html