Paget's disease of bone is a condition affecting how your bone breaks down and rebuilds. Healthy bone metabolism allows for old bone to be recycled into new bone throughout your life.

What is it?

Paget's disease of bone is a condition affecting how your bone breaks down and rebuilds. Healthy bone metabolism allows for old bone to be recycled into new bone throughout your life.

In Paget's disease of bone, the rate at which old bone is broken down and new bone is formed is distorted. Over time, Paget's disease of bone may result in your bones becoming fragile and misshapen.

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

Symptoms

Paget's disease of bone affects each person differently. Most people with Paget's disease have no symptoms. When symptoms do occur, they typically present in specific areas affected by the disease, although they may be widespread.

The condition usually affects the skull, the spine, and the bones in your arms, legs and pelvis. The disease may affect only one or two areas of your body, or may be widespread. Your symptoms, if any, will depend on the part of your body that's affected, including:

  • Bones. Pain in the affected bones is the most common symptom of Paget's disease of bone. Your pain may be constant, aching and deep, and may be most severe at night.
  • Joints. Paget's disease may damage the cartilage lining the joints near your affected bones. This wear and tear often leads to osteoarthritis in your affected joints, a condition that may cause pain, swelling and stiffness.
  • Nerves. Enlarged bones can compress your spinal cord or the nerves exiting your brain and spinal cord. Pain resulting from nerve compression is more severe than the bone pain associated with Paget's. The location of the pain caused by nerve compression depends on the nerve that's affected. You may notice pain radiating from your lower back into your legs (sciatica) if the lower region of your spine is affected. Pressure on a nerve can also cause numbness, tingling, weakness, hearing loss and double vision.

Other signs and symptoms of Paget's disease may include:

  • Warmth in your skin over the affected area
  • Neurological problems, such as hearing loss, headache and rarely, vision loss
  • Bone deformities, such as bowlegs and enlarged head size
  • Fractures

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 and heredity are the only known risk factors for Paget's disease of bone. Occasionally, the disease runs in families. People older than 40 are the most likely to develop Paget's disease. Men are more commonly affected than are women.

Complications

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

  • Osteoarthritis. This degenerative joint disease is a common long-term complication of Paget's disease.
  • 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.
  • Sarcoma. A rare complication is a bone cancer known as sarcoma, also called osteosarcoma or osteogenic sarcoma, which may develop in bones affected by Paget's disease. This complication occurs in less than 1 percent of people with Paget's disease and usually doesn't develop until many years after the onset of Paget's.

If the disease affects bones in your head, you may experience hearing loss, loss of teeth and, rarely, loss of vision.

Diagnosis

Detecting Paget's disease of bone early may help prevent serious complications. The following procedures may help your doctor detect Paget's disease of bone:

  • Blood test. If you have a sibling or parent with Paget's disease, talk to your doctor about requesting an alkaline phosphatase blood test every two to three years after age 40. Alkaline phosphatase is produced by bone cells that are responsible for forming new bone and is elevated in most people with Paget's disease.
  • X-rays. The first indication of Paget's disease is often either an elevated alkaline phosphatase level or 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. Your doctor may be able to base a diagnosis of Paget's disease on the bone X-ray findings.
  • Bone scan. In some cases, your doctor may recommend a bone scan. Bone scans can pick up Paget's disease before it can be seen on an X-ray. Doctors also use bone scans to determine which bones are affected. In a bone scan, radioactive tracers are injected into your body. The tracers are taken up by your bones and give off radiation that's captured by a special camera, which produces a picture of your skeleton. Areas of bone that are affected by Paget's disease are darker than normal on the scan.

References

http://emedicine.medscape.com/article/334607-overview

http://www.mayoclinic.org/diseases-conditions/pagets-disease-of-bone/home/ovc-20183843

https://www.hse.ie/eng/health/az/P/Paget's-disease/Causes-of-Paget's-disease.html

http://www.nhs.uk/Conditions/Pagets-disease/Pages/Symptoms.aspx