Definition

Paget's disease results in enlarged and deformed bones. It is a chronic (long-term) condition. Any bone in the body can be affected. However, the most common sites are the spine, skull, pelvis, thighs, and lower legs. The disease does not usually spread to other normal bones.

Normal Bone Structure

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Causes

Paget's disease is caused by a malfunction in bone formation. Normally, bones are constantly being broken down by cells called osteoclasts. They are then rebuilt by cells called osteoblasts. With Paget's disease, bones are broken down abnormally fast, and new bone replacement is loose and bulky, instead of strong and compact. These poorly formed bones may become weak. They also may bend over time.

The exact cause of this bone malformation is unknown. It is associated with family history. Some experts believe that Paget's disease may be triggered early in life by a viral infection.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. Risk factors for Paget's disease include:

• Family history of Paget's disease, especially in a parent, sibling, or child
• Race: Anglo-Saxon, European
• Age: 40 or older
• In United States, residence in northern states

Symptoms

In the early stages, most people have no noticeable symptoms. In later stages, symptoms may include:

• Swelling or deformity of a limb
• Increased head size
• Bowing of a limb
• Curvature of the spine
• Chronic bone pain, especially legs, hips, or spine
• Frequent fractures
• Problems with walking or gait
• Headaches, facial pain, or hearing loss (when the skull bones are affected)
• Swollen or painful joints due to damaged joint cartilage
• Numbness, tingling, pain, or weakness from pressure on nerves

Depending on the bone site, Paget's disease may result in:

• Arthritis, usually osteoarthritis
• Carpal tunnel syndrome
• High calcium in blood
• Kidney stones
• Hearing problems (common)
• Dental problems
• Rarely: eye problems, congestive heart failure, bone cancer (sarcoma)

Diagnosis

Your doctor will ask about your symptoms and medical history. He or she will do a physical exam. Tests may include:

• Blood tests—such as those for alkaline phosphatase or calcium
• X-ray—a test that uses radiation to take a picture of the bones
• Bone scan—a series of pictures of bones taken after injection of a small amount of radioactive material

Treatment

It is best to begin treatment as soon as possible. Treatment options include:

Prevention

There is no known way to prevent the onset of Paget's disease. People with primary family members who have Paget's disease are encouraged to have a routine alkaline phosphatase blood test every 2-3 years after age 40.