Paget's disease of bone

Definition

Paget's disease of bone is a condition that affects the way your bone breaks down and rebuilds (metabolizes). Healthy bone metabolism allows for old bone to be recycled into new bone throughout the course of your life. In Paget's disease of bone, the rate at which old bone is broken down and new bone is formed becomes distorted. Over time, the affected bones may become fragile and misshapen.

Paget's disease of bone becomes more common with age. Many older people who experience discomfort in their bones and joints assume that those symptoms are a natural part of aging, and therefore don't seek treatment. But to prevent the most serious complications of Paget's disease of bone, it's critical to get treatment as soon as possible after signs and symptoms appear.

Paget's disease of bone

Paget's disease of bone

On the right, an X-ray of an upper arm bone (humerus) shows the abnormal growth associated with Paget's disease. The same person's other, normal humerus is shown in the X-ray on the left. ...

Symptoms

Most people who have Paget's disease of bone experience no symptoms. When symptoms do occur, the most common complaint is bone pain. The disease may affect only one or two areas of your body, or may be widespread. Your signs and symptoms, if any, will depend on the part of your body that's affected, including:

• Pelvis. Paget's disease of bone in the pelvis can cause hip pain.
• Skull. An overgrowth of bone in the skull can cause hearing loss or headaches.
• Spine. If your spine is affected, nerve roots can become compressed. This can cause pain, tingling and numbness in an arm or leg.
• Leg. As the bones weaken, they may bend — causing you to become bow-legged. Enlarged and misshapen bones in your legs can put extra stress on nearby joints, which may cause wear-and-tear arthritis in your knee or hip.

When to see a doctor
Talk to your doctor if you have:

• Pain in your bones and joints
• Tingling and weakness
• Bone deformities

Causes

Even after you've reached your full height, your bones don't stop growing. Bone is living tissue engaged in a continual process of renewal. During this constant process called remodeling, old bone is removed and replaced by new bone. Paget's disease of bone disrupts this process.

Early in the course of the disease, old bone starts breaking down faster than new bone can be built. Over time, your body responds by generating new bone at a faster than normal rate. This rapid remodeling produces bone that's softer and weaker than normal bone, which can lead to bone pain, deformities and fractures.

Scientists haven't identified a cause of Paget's disease of bone, though they have discovered several genes that appear to be linked to the disorder.

Some scientists believe Paget's is related to a viral infection in your bone cells that may be present for many years before problems appear. Hereditary factors seem to influence whether you're susceptible to the disease.

Risk factors

• Age. People older than 40 are the most likely to develop Paget's disease of bone.
• Sex. Men are more commonly affected than are women.
• National origin. Paget's disease of bone is more common in people of Anglo-Saxon descent.
• Family history. If you have a close relative who has Paget's disease of bone, you are much more likely to develop the condition yourself.

Complications

In most cases, Paget's disease of bone progresses slowly. The disease can be managed effectively in nearly all people. Possible complications include:

• Fractures. Bones affected by Paget's disease are large and dense, but also weak and brittle. This makes them more prone to fractures. More blood vessels are created in these deformed bones, so they bleed more during repair surgeries.
• Osteoarthritis. Misshapen bones can increase the amount of stress on nearby joints, which can cause osteoarthritis.
• Heart failure. Unusually extensive Paget's disease may force your heart to work harder to pump blood to the affected areas of your body. In people with pre-existing heart disease, this increased workload can lead to heart failure.
• Bone cancer. Bone cancer occurs in less than 1 percent of people with Paget's disease.

Preparing for your appointment

Most people with Paget's disease of the bone don't have any symptoms and are diagnosed when an X-ray or blood test taken for another reason reveals signs of Paget's disease. In some cases, you may be referred immediately to a doctor who specializes in metabolic and hormonal disorders (endocrinologist) or in bone and muscle disorders (rheumatologist).

What you can do
Before your appointment, you may want to write a list that answers the following questions:

• What symptoms, if any, do you have? When did they start?
• Have any of your relatives had Paget's disease of bone?
• What medications or supplements are you taking?

What to expect from your doctor
During the physical exam, your doctor will carefully examine any areas of your body that are causing you pain. He or she may also order X-rays and blood tests that can help confirm the diagnosis of Paget's disease of bone.

Tests and diagnosis

A variety of tests can confirm a diagnosis of Paget's disease of bone. Your doctor also may order these types of tests during treatment, to see if the medications are working.

Imaging tests

• X-rays. The first indication of Paget's disease is often abnormalities found on X-rays done for other reasons. X-ray images of your bones can show areas of bone reabsorption, enlargement of the bone and deformities that are characteristic of Paget's disease, such as bowing of your long bones.
• Bone scan. In a bone scan, radioactive material is injected into your body. This material travels to the spots on your bones most affected by Paget's disease, so they light up on the scan images.

Lab tests
People who have Paget's disease of bone usually have elevated levels of alkaline phosphatase in their blood. They may also have increased amounts of hydroxyproline in their urine, particularly if the disease affects more than one bone.

Paget's disease of bone

Paget's disease of bone

On the right, an X-ray of an upper arm bone (humerus) shows the abnormal growth associated with Paget's disease. The same person's other, normal humerus is shown in the X-ray on the left. ...

Treatments and drugs

If you don't have symptoms, you may not need treatment. However, if the disease is active — indicated by an elevated alkaline phosphatase level — and is affecting high-risk sites in your body, such as your skull or spine, your doctor may recommend treatment to prevent complications, whether or not you have symptoms.

Medications
Osteoporosis drugs (bisphosphonates) are the most common treatment for Paget's disease of bone. Some bisphosphonates are given as oral medications, while others are given by injection. Oral bisphosphonates are generally well tolerated, but may irritate your gastrointestinal tract. Examples include:

• Alendronate (Fosamax)
• Ibandronate (Boniva)
• Pamidronate (Aredia)
• Risedronate (Actonel)
• Zoledronic acid (Zometa, Reclast)

If you can't tolerate bisphosphonates, your doctor may prescribe calcitonin (Miacalcin), a naturally occurring hormone involved in calcium regulation and bone metabolism. Calcitonin is a drug that you administer to yourself by injection. Side effects may include nausea, facial flushing and irritation at the injection site.

Surgery
In rare cases, you may require surgery to:

• Help fractures heal
• Replace joints damaged by severe arthritis
• Realign deformed bones
• Reduce pressure on nerves

Paget's disease often causes the body to produce an excessive number of blood vessels in the affected bones. This change increases the risk of serious blood loss during an operation. If you're scheduled for surgery that involves bones affected by Paget's disease, your doctor may prescribe medications to reduce the activity of the disease, a step that tends to reduce blood loss during surgery.

Lifestyle and home remedies

• Prevent falls. Paget's disease puts you at high risk of bone fractures. Ask your doctor for advice on preventing falls. He or she may recommend that you use a cane or a walker. Take measures to fall-proof your home. Remove slippery floor coverings, use nonskid mats in your bathtub or shower, tuck away cords, and install handrails on stairways and grab bars in your bathroom.
• Eat well. Be sure your diet includes adequate levels of calcium and vitamin D, which facilitates the absorption of calcium. This is especially important if you're being treated with bisphosphonates. Review your diet with your doctor and ask if you should begin taking vitamin and calcium supplements.
• Exercise regularly. Exercising on a regular basis is essential for maintaining joint mobility and bone strength. Talk to your doctor before beginning an exercise program to determine the right type, duration and intensity of exercise for you. Some activities may place too much stress on your affected bones.