Paget's Disease of Bone
Paget's disease of bone, or Paget's disease, is a chronic disorder that interferes with bone metabolism, causing bones to grow too large and become fragile. Even in full-grown adults, bones continue to grow in order to renew themselves, a process known as remodeling. Paget's disease disrupts this normal bone-recycling process, commonly affecting the spine, pelvis, skull or legs. At the onset, the disease causes old bone to deteriorate more quickly than new bone can be created. As the disorder progresses, the body responds by generating new bone at an abnormally rapid rate. This new bone is soft and weak, leading to pain, possible fractures and deformities.
Unlike some bone disorders, such as osteoporosis, Paget's disease may affect only one or two bones in the body. This disorder is more common in men than women and typically affects those older than 40 years of age. Paget's disease may lead to fractured bones, arthritis, and in severe cases, heart failure or nervous system problems.
Causes of Paget's Disease
The precise cause of Paget's disease has not been determined, but the risk of developing the disorder increases with age and family history of the disease. Some researchers speculate that the disorder is precipitated by a viral infection within the bones, causing symptoms to appear years later, and that a hereditary weakness predisposes some people to develop the problem, since several genes have been linked to Paget's disease. There is also some evidence that Paget's may be an autoimmune disorder.
Symptoms of Paget's Disease
At its onset, Paget's disease presents with symptoms so mild that patients may be unaware of them, but, as the disease progresses, the symptoms become more troubling. These symptoms vary depending upon which bones are affected. Overgrowth of bone in the skull, for example, may lead to headaches or hearing loss. When Paget's disease attacks the leg bones, patients may become bowlegged, and if Paget's targets the spine, patients may experience pain, loss of sensation, or tingling in the arms and legs.
In general, the symptoms of Paget's disease include:
- Bone pain
- Enlarged bones
- Bone fractures
- Stiffness or weakness
- Bending of bones or other bone deformity
- Osteoarthritis and damaged joints
- Tingling or numbness in the extremities
The majority of patients with Paget's disease experience no symptoms. When symptoms are present, the most common one is bone pain. The disease may affect only a single area of the body or many regions simultaneously.
Diagnosis of Paget's Disease
To diagnose Paget's disease the doctor will review all symptoms and perform a complete physical examination. If the disease is suspected, diagnostic tests are performed, including X-rays, a bone scan, and a test to detect excessive alkaline phosphatase in the blood, a sign of the disorder.
Treatment of Paget's Disease
Patients who are asymptomatic may not require any treatment, but are advised to be proactive in preserving bone health by eating a healthy diet with sufficient levels of calcium and vitamin D, and by exercising regularly to keep their joints mobile.
When symptoms are present, depending on their severity, one or more of the following medications or surgeries may be necessary:
- Bisphosphonates (osteoporosis medications)
- Calcitonin, a hormone to regulate bone metabolism
- Surgery to repair fractured or deformed bone
- Surgery to relieve nerve compression
- Surgery to replace joints damaged by arthritis
There are side effects and more serious risks associated with medications used to treat Paget's disease. Bisphosphonates, such as Fosamax, are often associated with gastrointestinal irritation. These medications also increase the risk of osteonecrosis of the jawbone, and of a rare condition that causes the upper thighbone to crack. The alternative medication prescribed, Calcitonin, may cause unpleasant side effects, such as nausea, facial flushing and irritation at the site of administration.
Complications of Paget's Disease
Because Paget's disease causes the body to produce an excessive number of blood vessels in affected bones, it presents a risk of serious blood loss during any surgery involving affected bones. For this reason, patients scheduled for such surgery are premedicated to avoid complications. Because advanced Paget's disease causes the heart to work harder, there is some risk of heart failure, particularly in patients with pre-existing heart disease. Bone cancer is a rare complication of this disorder, occurring in less than 1 percent of cases.
Fortunately, in most patients, Paget's disease progresses slowly, and most people with the disease can be treated effectively.