Paget’s Disease Can Boost Fracture Risk

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Paget’s disease doesn’t get a lot of attention, but it’s the second most common bone disease after osteoporosis. Named for a 19th-century British surgeon, Sir James Paget, who was the first to describe its clinical features, the disease causes some bones to enlarge abnormally, affecting their size and shape and making them softer, more fragile, and prone to fracture.

Paget’s is a chronic disease that in many people progresses slowly. An estimated one million people in the United States have this sometimes-painful condition, and the risk increases with age.

Many of those affected do not have symptoms and do not need treatment—they may be unaware they have the disease until a routine blood test or X-ray suggests the diagnosis. When treatment is needed, it typically involves the use of bisphosphonates, the same class of bone-strengthening drugs used for osteoporosis. The goal with these medications is to relieve pain and prevent fractures and other disease complications.

Paget’s, explained
Bones are in a constant state of renovation, or remodeling. Cells called osteoclasts break down and absorb old bones, while osteoblasts build new bone. Think of this process as a home exterior renovation in which you remove old bricks a few at a time, then gradually replace them with new bricks.

In Paget’s, the remodeling process is thrown off balance. Osteoclasts become more active and numerous than usual. In a rush to catch up, osteoblasts hastily rebuild. While healthy bone fits together snugly like the bricks in your home, the quickly reconstructed bone fits together haphazardly and too loosely. The result is large, dense bones that are brittle, deformed, and more likely to fracture.

Paget’s disease can affect any bone in the body, but it’s most likely to occur in the spine, pelvis, long bones of the legs, and skull. Because the disease is progressive, it worsens over time. Catching it early may prevent it from becoming disabling.

Who gets Paget’s?
You’re more likely to get Paget’s disease if you’re of Anglo-Saxon heritage. The prevalence increases with age, striking most often in those over 55.

Paget’s tends to run in families. Studies suggest that people who have a close relative with the condition are up to 10 times more likely to develop the disease than those without a family history. Researchers have linked the condition to a few gene variants involved in bone remodeling.

It’s possible that a combination of genes and environmental factors sets off the disease. One theory is that infection with a virus such as measles triggers the bone damage.

Hidden disease
In most cases, Paget’s disease doesn’t cause any symptoms, but complications such as bone fractures and hearing loss may have occurred by the time of diagnosis. The reason why Paget’s disease causes hearing loss is not well understood, although bony involvement around the hearing structures of the ear may play a role.

Among people who do have symptoms, the most common one is pain. Other possible symptoms and complications of the disease include:

  • Bone fractures
  • Bowing or other deformities of the legs that can affect walking
  • Osteoarthritis when bones near a joint are affected
  • Numbness or weakness from pressure of a bone on a nerve
  • High levels of calcium in the blood (usually due to a coexisting disorder, such as an overactive parathyroid gland)
  • Hearing loss, headaches, and dizziness when the disease affects the skull bones
  • Osteosarcoma—a type of bone cancer that is rare, affecting fewer than 1 percent of people with Paget’s disease

Doctors confirm the diagnosis with X-rays and a blood test called serum alkaline phosphate (ALP). ALP is an enzyme involved in bone growth. A higher-than-normal level is a sign the bones are turning over at a too-rapid pace.

Once Paget’s is diagnosed, a bone scan can reveal which bones the disease has affected. This test uses a radioactive dye, which is absorbed in greater quantities by bones with increased turnover.

Remission is possible
The treatment of choice for Paget’s is potent bisphosphonates— the same class of drugs used to slow or stop bone loss in people with osteoporosis. Because not everyone with Paget’s needs to be treated, doctors typically recommend bisphosphonates for people who are at risk for complications.

Bisphosphonates are usually given for a limited time, and require regular follow-up with ALP blood tests—typically every three to six months—to see if treatment is working. People whose ALP levels drop to normal are said to be in remission, and may be able to stop therapy.

While taking a bisphosphonate, it is important to consume sufficient—but not excessive—calcium and vitamin D every day, preferably through diet.

Several bisphosphonates are approved for Paget’s disease. The Endocrine Society recommends a single 5 mg intravenous dose of zoledronate (Reclast), because it is well tolerated and can put people into long-term remission. People rarely need a second dose within five years.

Oral bisphosphonates like alendronate (Fosamax) and risedronate (Actonel) are also effective. However, these drugs require higher doses and a longer course of treatment—typically two to six months of daily pills. An older intravenous drug, pamidronate (Aredia), is also approved for Paget’s. Bisphosphonates can cause side effects. The most common ones are mild, such as heartburn with oral formulations, or flu-like symptoms with intravenous ones. Rarely, eye inflammation (uveitis) and kidney damage may also occur with intravenous bisphosphonates.

While bisphosphonates are the standard treatment recommended by the Endocrine Society for people at risk of complications, recent research has been investigating whether controlling symptoms with nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, and other pain relievers might be just as effective, with fewer side effects. However, NSAIDs have been linked to side effects such as heart attack, stroke, stomach ulcers, and bleeding, and their long-term use is particularly risky in older adults. While NSAIDs may help people with symptoms, they are unlikely to control the long-term complications of Paget’s disease.

Bottom line
If you are diagnosed with Paget’s disease, you’ll need to be carefully evaluated by a specialist—typically an endocrinologist. An experienced physician will assess the pros and cons of therapy, based on your unique risks and symptoms, and discuss them with you before treatment starts.