What is HPP?

HPP is a rare, inherited metabolic bone disease. Patients have low levels of an enzyme called Alkaline Phosphatase (ALP).

Why is ALP important?

This enzyme is critical for hardening (mineralizing) bones and teeth. Without it, bones stay soft and fragile.

Signs and Symptoms:

• Teeth: Losing baby teeth early (before age 5), often with the root still intact.
• Bones: Soft bones (rickets), bowed legs, frequent fractures, or bone pain.
• Muscles: Profound muscle weakness or difficulty walking.

Diagnosis:

It is often misdiagnosed as osteoporosis or nutritional rickets. The key clue is a LOW Alkaline Phosphatase level on a blood test (whereas in most other bone diseases, this level is high).

Treatment:

• Enzyme Replacement Therapy: A medication called Asfotase Alfa (Strensiq) replaces the missing enzyme. It is an injection given several times a week. It has revolutionized treatment, allowing children with severe forms to survive and walk.
• Avoid Bisphosphonates: Common osteoporosis drugs can actually make HPP worse.