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Paget's disease of bone is a chronic bone disorder. Normally, there is a process in which your bones break down and then regrow. In Paget's disease, this process is abnormal. There is excessive breakdown and regrowth of bone. Because the bones regrow too quickly, they are bigger and softer than normal. They may be misshapen and easily fractured (broken). Paget's usually affects just one or a few bones.

Researchers do not know for sure what causes Paget's disease. Environmental factors may play a role. In some cases, the disease runs in families, and several genes have been linked to the disease.

The disease is more common in older people and those of northern European heritage. If you have a close relative who has Paget's, you are much more likely to have it.

Many people do not know that they have Paget's, because it often has no symptoms. When there are symptoms, they are similar to those of arthritis and other disorders. The symptoms include:

• Pain, which may be due to the disease or to arthritis, which can be a complication of Paget's
• Headaches and hearing loss, which can happen when Paget's disease affects the skull
• Pressure on the nerves, which can happen when Paget's disease affects the skull or spine
• Increased head size, bowing of a limb, or curvature of the spine. This can happen in advanced cases.
• Hip pain, if Paget's disease affects the pelvis or thighbone
• Damage to the cartilage of your joints, which may lead to arthritis

Usually, Paget's disease gets worse slowly over time. It does not spread to normal bones.

Paget's disease can lead to other complications, such as:

• Arthritis, because the misshapen bones can cause increased pressure and more wear and tear on the joints
• Heart failure. In severe Paget's disease, the heart has to work harder to pump blood to affected bones. Heart failure is more likely if you also have hardening of the arteries.
• Kidney stones, which can happen when the excessive breakdown of the bone leads to extra calcium in the body
• Nervous system problems, since the bones can cause pressure on the brain, spinal cord, or nerves. There may also be reduced blood flow to the brain and spinal cord.
• Osteosarcoma, cancer of the bone
• Loose teeth, if Paget's disease affects the facial bones
• Vision loss, if Paget's disease in the skull affects the nerves. This is rare.

Your health care provider may use many tools to make a diagnosis:

• A medical history, which includes asking about your symptoms
• A physical exam
• An x-ray of the affected bones. Paget's disease is almost always diagnosed using x-rays.
• An alkaline phosphatase blood test
• A bone scan

Sometimes the disease is found by accident when one of these tests is done for another reason.

To avoid complications, it is important to find and treat Paget's disease early. The treatments include:

• Medicines. There are several different medicines to treat Paget's disease. The most common type is bisphosphonates. They help reduce bone pain and stop or slow down the progress of the disease.
• Surgery is sometimes needed for certain complications of the disease. There are surgeries to
  • Allow fractures (broken bones) to heal in a better position
  • Replace joints such as the knee and hip when there is severe arthritis
  • Realign a deformed bone to reduce the pain in weight-bearing joints, especially the knees
  • Reduce pressure on a nerve, if enlargement of the skull or spine injuries effects the nervous system

Diet and exercise do not treat Paget's, but they can help to keep your skeleton healthy. If you do not have kidney stones, you should make sure to get enough calcium and vitamin D through your diet and supplements. Besides keeping your skeleton healthy, exercise can prevent weight gain and maintain the mobility of your joints. Talk with your health care provider before you start a new exercise program. You need to make sure that the exercise does not put too much stress on the affected bones.

NIH: National Institute of Arthritis and Musculoskeletal and Skin Diseases

Your bones help you move, give you shape and support your body. They are living tissues that rebuild constantly throughout your life. During childhood and your teens, your body adds new bone faster than it removes old bone. After about age 20, you can lose bone faster than you make bone. To have strong bones when you are young, and to prevent bone loss when you are older, you need to get enough calcium, vitamin D, and exercise. You should also avoid smoking and drinking too much alcohol.

Bone diseases can make bones easy to break. Different kinds of bone problems include:

• Low bone density and osteoporosis, which make your bones weak and more likely to break
• Osteogenesis imperfecta makes your bones brittle
• Paget's disease of bone makes them weak
• Bones can also develop cancer and infections
• Other bone diseases, which are caused by poor nutrition, genetics, or problems with the rate of bone growth or rebuilding

NIH: National Institute of Arthritis and Musculoskeletal and Skin Diseases

Most people have four pea-sized glands, called parathyroid glands, on the thyroid gland in the neck. Though their names are similar, the thyroid and parathyroid glands are completely different. The parathyroid glands make parathyroid hormone (PTH), which helps your body keep the right balance of calcium and phosphorous.

If your parathyroid glands make too much or too little hormone, it disrupts this balance. If they secrete extra PTH, you have hyperparathyroidism, and your blood calcium rises. In many cases, a benign tumor on a parathyroid gland makes it overactive. Or, the extra hormones can come from enlarged parathyroid glands. Very rarely, the cause is cancer.

If you do not have enough PTH, you have hypoparathyroidism. Your blood will have too little calcium and too much phosphorous. Causes include injury to the glands, endocrine disorders, or genetic conditions. Treatment is aimed at restoring the balance of calcium and phosphorous.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases