Throughout your life, your body is continually absorbing (breaking down) bone and building new bone. If you have Paget disease, this process is greatly speeded up.

Researchers say a "slow virus" infection may be the main cause of the illness. A slow virus infection is one that works on the body for many years. A gene may also play a role in the disease. Paget disease tends to run in families.

It is rare in people younger than 40. Both men and women can develop Paget disease.

Although it is not arthritis, Paget disease can lead to arthritis. This happens as damaged bones put pressure on nearby joints or cause excessive wear and tear on joints. In many cases, however, people don’t know they have Paget disease because they have no symptoms. When symptoms do appear, they include bone pain, fractures, headache (if bones in the skull or spine are affected), hearing loss (because of damage to the small bones in the ear), curvature of the spine, pressure on nerves, and hip pain. Symptoms get worse slowly.

Any bone in the body can be affected by Paget disease. But the bones most commonly affected are those in the spine, skull, pelvis, thighs, and lower legs. Usually, Paget affects only 1 or 2 bones, and sometimes only part of a bone.

A bone scan can tell your health care provider how much bone is affected by the disease. An X-ray can confirm a diagnosis of the disease. This is because affected bones have a particular look on an X-ray. A higher level of alkaline phosphatase can mean that you have Paget disease. People with a family history of the disease can have their alkaline phosphatase level checked every 2 to 3 years. If the test is positive, treatment can begin right away.

When Paget disease affects the bones of the inner ear, you may have hearing loss in one or both ears. In people with severe Paget disease, the heart works harder to pump blood to the bones affected by the disease. This can cause problems if the person also has hardening of the arteries. A person with Paget is also more likely to develop kidney stones. Other disorders linked to Paget include nervous system problems, loose teeth, and rarely, vision loss.

For many cases of Paget disease, no treatment is needed. When pain is present, a nonsteroidal anti-inflammatory medicine can offer relief. Steroids also may be prescribed. More severe cases can be treated with bisphosphonates or calcitonin. Exercise also is important. Talk with your health care provider to find out which type of exercise is best.