Paget's disease

Definition
Paget's disease, also known as osteitis deformans, is a chronic disease of the skeleton characterized by an excessive breakdown of bone, which is followed by a rapid, disorganized formation of new bone. This hasty formation of disorganized bone causes bone enlargement, deformity and fragility. Although Paget's disease typically affects bones of the spine, pelvis, legs and skull, any bone can be affected.

Causes/associated factors
The cause of Paget's disease is unknown. Recent studies indicate the condition may be related to a slowly developing viral infection that's in the body many years before causing symptoms. Viral particles of the paramyxovirus has been detected in affected bones. Because the disease may appear in more than one family member, there's also thought to be a hereditary factor. This may be due to susceptibility to the associated virus, however.
Paget's disease is most common in Caucasians of British descent, but it does occur in African Americans. It rarely affects people of Asian, Nordic or Middle Eastern heritage, and it affects men and women about equally. It's rare in people under age 40. Up to 3 percent of people in the United States over age 40 have some degree of Paget's disease.


Signs/symptoms
Most people who have Paget's disease have a mild illness without symptoms. Many are diagnosed through routine blood testing or an X-ray done for other reasons. The disease may occur in only one bone or in multiple bones. It doesn't spread from bone to bone. Depending on which bone(s) are affected, symptoms may include:
dull, boring pain in the affected bones (such as in the hip, back or leg) and sometimes adjacent joints
deformities, such as increased head size, bowing of a limb or curvature of the spine (caused by the enlargement or softening of affected bones)
loose teeth, if the jaw is affected
headaches, hearing or vision loss, vertigo (dizziness or feeling unbalanced) or tinnitus (ringing in the ears), if the skull is affected
increased warmth over affected areas (caused by increased blood flow to the affected area)

Diagnosis
Along with standard blood and urine tests, your doctor may order more specific tests to diagnose Paget's disease. For example, Paget's disease causes an elevation in levels of serum alkaline phosphatase, a product of bone-forming cells. A specialized blood test, called bone-specific alkaline phosphatase, may also be done. Other bone-specific products can be identified in the urine, such as pyridinoline.
Bone scans are helpful in the early detection of Paget's disease because bone changes are often visible before they can be seen with an X-ray. Later, simple X-rays can identify the affected bones. Bone biopsies are seldom used for diagnosis unless malignancy (cancer) is suspected.


Treatment
The sooner the condition is diagnosed and treated, the better the outcome. Your doctor may refer you to a specialist, such as an endocrinologist (hormonal and metabolic specialist) or rheumatologist (joint and muscle specialist). Others may be recommended to treat specific symptoms that may occur with Paget's disease, including an orthopedist (musculoskeletal specialist), an otolaryngologist (ear, nose and throat specialist) or a neurologist (nervous system specialist).
If you have no symptoms, you may not require treatment. Maintaining your weight within an ideal range may help reduce stress on affected bones, as well as maintain joint function and mobility. To promote skeletal health, exercise may be recommended. Remember to consult your doctor before beginning an exercise program.

Medication
For mild symptoms with little bone involvement, the doctor may recommend acetaminophen or nonsteroidal anti-inflammatory pain relievers, such as ibuprofen or naproxen.

For more extensive disease, medication may be used to relieve symptoms, help slow the progression of the disease and prevent complications. The U.S. Food and Drug Administration has approved several bisphosphonates (medications that inhibit abnormal bone resorption) to treat Paget's disease. These medications are highly effective in treating Paget's disease and can even slow the disease activity for months to years after medication is stopped. Those used most often include alendronate sodium (brand name Fosamax), etidronate (Didronel), risedronate sodium (Actonel), and tiludronate (Skelid) which are taken by mouth, and pamidronate disodium (Aredia) which is given by intravenous (IV) infusion.

Calcitonin (a hormone that helps form healthy bones) has also been successfully used to treat Paget's disease. It's used most often when treatment with bisphosphonates is not tolerated well.

Surgery
Surgery is reserved for people who have severe complications. Grossly malformed bones may be cut and realigned properly through a surgical procedure called an osteotomy. Knee or hip replacements may be done to treat severe pain or in cases where medical treatment fails. Surgery to treat Paget's disease should only be done at medical centers staffed by doctors with experience in this difficult bone surgery.


Complications
Bone fractures are common and can occur with minimal trauma or stress to the bone. With timely medical treatment, complications are rare. When they do occur they may include:
heart failure due to increased blood flow in affected areas
hearing loss
severe degenerative arthritis in joints near the affected bones
kidney stones
spinal cord compression due to bony overgrowth or the collapse of affected vertebrae (the bony sections that make up the spine), which may result in weakness or paralysis of the legs
osteosarcoma (a cancerous tumor of the bone that occurs in less than 1 percent of people who have Paget's disease; despite medical intervention, osteosarcoma often has a poor prognosis)

Pregnancy-specific information
Because Paget's disease tends to develop in middle age, the chance of occurrence during pregnancy is rare.

Senior-specific information
The risk of developing Paget's disease increases with age. It may be difficult to distinguish the pain of Paget's disease from pain due to other bone or joint conditions. Bones are often weakened by osteoporosis, for example, and arthritis may lead to joint stiffness. The occurrence of certain fractures increases with age, particularly hip fractures. Be sure to consult your doctor if you experience any bone or joint pain.