AN UNUSUAL BONE DISEASE: Paget’s Disease

By Noga C. Minsky, MD

Paget’s disease is a condition that affects the normal process by which the bone breaks down and rebuilds itself (remodeling). Throughout the course of your life, old bone is removed from the skeleton and new bone is formed. New bone tissue is laid down in organized layers of fibers running in opposite directions, like plywood. This makes the bone strong and compact. In Paget’s disease, the bone break down is in overdrive, which is followed by rapid, disorganized formation of weak and expanded bone. Affected bones may become fragile, which can lead to bone pain, deformities, and fractures.

This disease affects many Americans but is often undiagnosed. Up to 3% of people over 40 years of age are affected, and it goes up with age. Paget’s disease is most common in whites.

WHAT ARE THE SYMPTOMS?

Only 10%-30% of patients with Paget’s disease have symptoms. Bone pain is the most common symptom. Most of the time, more than one bone is affected. All bones may be involved, but most commonly the skull, spine, and pelvis are affected. Signs and symptoms depend on the part of the body that is affected:

  • Skull. Bony overgrowth can cause the skull to grow, with the patient having headaches, hearing loss, and other nerve complications.
  • Spine. Nerve roots can become “pinched” or blood flow can decrease. This can cause arm or leg pain, weakness, or tingling and numbness.
  • Pelvis. Paget’s disease affecting the pelvis can cause hip pain.
  • Leg. Weak bone can bend and lead to bowing of the leg.
WHAT ARE THE COMPLICATIONS?

Paget’s disease normally progresses very slowly. Complications can be managed medically and surgically. Possible complications include:

  • Osteoarthritis. Deformed bones can increase the amount of stress on nearby joints, which can cause osteoarthritis [ah-steeoh-arth-RITE-iss].
  • Fractures. Bones affected by Paget’s disease are large but also fragile and more likely to break. These deformed bones have more blood vessels, so there is a tendency for them to bleed during surgical repairs.
  • Heart failure. Very extensive Paget’s disease can increase the workload on the heart because it pumps more blood to the affected bones. Rarely, this can lead to heart failure.
  • Bone cancer. Bone cancer occurs in less than 1% of people with Paget’s disease and shows up as an enlarging mass.

WHAT ARE THE CAUSES?

Your family history determines if you are at risk for the disease. If your relative mother, father, or sibling has Paget’s disease, you are 10 times more likely to be affected. Also, some scientists believe the disease may occur from viral infection.

HOW IS IT DIAGNOSED?

Doctors check for high blood alkaline phosphatase [FOS-fuh-tase] levels, which means that bone is being formed at a rapid rate. The doctor will then order a bone scan to determine which parts of the skeleton are affected. Radioactive material is injected into the body and this material travels to the involved bones and lights up on imaging. X-rays are performed of these “hot spots,” showing areas of bone breakdown, enlarged bone, and bone deformities.

WHEN AND HOW SHOULD PAGET’S DISEASE BE TREATED?

The Paget Foundation has guidelines on when the disease should be treated. Therapy is given when there are symptoms such as pain or when complications occur. Treatment should also be given before operating on an affected bone to reduce bleeding. Many investigators believe that treatment is indicated even in patients with no symptoms but whose disease involves the skull, spine, and long leg bones. The reason is because these patients have a high risk for complications.

Drugs called bisphosphonates [bis-FOS-fuh-nates] are the treatment of choice. These are also used to treat osteoporosis and are very effective for Paget’s disease. Treatment returns bone formation to a normal rate. The most effective medication is intravenous zolendronic [zo-len-DROH-nik] acid since it is a one-time treatment. This medicine is given by slow drip into a vein over 15 minutes. It works in nearly 90% of patients and its effect lasts at least two years. Intravenous pamidronate [puh-MIH-dro-nate] and oral bisphosphonates, such as risendronate [rih-SEHdruh-nate] and alendronate [uh-LEN-dro-nate] may also be used. When bisphosphonates are not tolerated, calcitonin [cal-sih-TOE-nin], a natural hormone involved in bone metabolism, can be used. In rare cases of severe complications, surgery may be required.

Paget’s disease affects millions of Americans, and frequently goes undiagnosed. It is important for patients to tell their doctors if they experience suspicious symptoms or have a family history of the disease because therapies are available that can treat and may prevent serious complications.

Dr. Noga C. Minsky is in medical practice at Mount Sinai in New York City. She is board certified in Internal Medicine and as a Physician Nutrition Specialist. She is actively involved in thyroid cancer research and has previously presented original research on vitamin D and ovarian hormonal production at a national conference, The Endocrine Society. She has published in peer-reviewed medical journals and has written a book chapter on the management of inpatient thyroid disease.