What Is Hypophosphatasia?

What Is Hypophosphatasia?


Signs and Symptoms

Everyone experiences HPP differently.

The signs and symptoms of HPP vary from patient to patient. Not everyone with HPP has every symptom. Bones and teeth are most often affected.  Bones can be weakened, which may result in fractures. Baby teeth can fall out earlier than normal, as well as adult teeth.

In a recent combined review of two studies of people who have HPP, 1 in 8 people had severe bone pain, 1 in 8 had joint pain, and more than 1 in 5 people had muscle pain.

Age of onset and severity of HPP

Generally, the younger a person is when diagnosed with HPP, the more serious the signs and symptoms, with the exception of odontohypophosphatasia (HPP affecting only teeth). Doctors usually define the illness based on the person’s age at the time of diagnosis.

As in other rare conditions, many doctors confuse the symptoms of HPP with symptoms of other diseases. This can make getting a diagnosis difficult. But keeping track of your symptoms and having a good relationship with your doctor can help.

HPP signs and symptoms

Perinatal (before, during, and after birth) onset

  • In perinatal HPP, the disease is apparent at birth
  • Infants with HPP are born with short limbs, abnormal chest shape, and soft skull bones
  • This is the most severe type of HPP with very serious complications. Parents whose children are expected to have perinatal HPP should consult an HPP specialist for a detailed and expert evaluation

Infantile onset

  • Infantile HPP appears from shortly after birth to 6 months of age
  • HPP in infants is often more severe than it is in older children. It is estimated that for 1 in 2 infants with infantile onset of the disease, HPP leads to death  
  • Bones in all parts of the body can become weak and soft, causing changes in the skeleton. This can lead to rickets, in which legs are bowed because bones are not shaped correctly
  • Infants with HPP can also have difficulty gaining weight and problems with eating and breathing. Also, too much calcium in the blood can cause vomiting and kidney problems. These problems can be serious and lead to the death of the infant

Childhood onset

  • Childhood onset of HPP is often less severe than HPP in infants
  • Baby teeth typically fall out earlier than normal. This can also be one of the first signs of HPP. Parents of children with HPP should not be surprised by this loss of teeth
  • Legs may appear bowed or “knock-kneed,” wrist or ankle joints may be enlarged, and the skull may not be shaped normally

Adult onset

  • Typically appears in middle age
  • Fractures often reoccur in the feet and heal slowly
  • Adult bones can become soft (a condition called osteomalacia)
  • Adults with HPP sometimes remember having rickets or losing their baby teeth early
  • Adults may also lose their teeth early
  • There may be an increased risk for joint pain and swelling


  • This is the mildest form of HPP. It affects the normal stability of teeth and may cause them to fall out
  • Bones are not affected by this condition
  • This condition does not include problems such as rickets or broken bones

HPP can affect organs and body systems other than bones and teeth. This is because normal substances in your blood and body can build up and become harmful. These substances include calcium and phosphate. When these substances build up, they can cause symptoms that doctors don’t recognize as HPP, such as stomach problems and vomiting. Because these symptoms may not be recognized as HPP, it can be hard for a doctor to diagnose HPP correctly.


It can help to learn what other people with HPP have experienced. Learn more from patient community Web sites. For more information on how HPP can affect other parts of your body, read about the Science of HPP.

I like to remind patients who have just received a diagnosis of hypophosphatasia not to panic. It is a complex disease with different forms and a wide range of symptoms. Each patient is unique. But being informed about other patients’ experiences can help you understand when you need to be vigilant and what you might need to prepare for. Steve Ursprung, Founder, Hypophosphatasie Europe

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Why HPP is hard to diagnose