Thin bones; Low bone density

Osteoporosis is the most common type of bone disease.

Because of osteoporosis about half of all women over the age of 50 will have a fracture of the hip, wrist, or vertebra (bone of the spine) during their lifetime.

Bone is living tissue. Existing bone is constantly being replaced by new bone. Osteoporosis occurs when the body fails to form enough new bone, when too much existing bone is reabsorbed by the body, or both.

Calcium is one of the important minerals needed for bones to form. If you do not get enough calcium and vitamin D, or your body does not absorb enough calcium from your diet, your bones may become brittle and more likely to fracture.

Sometimes bone loss occurs without any cause. Caucasian women are more likely to have bone loss. Sometimes the tendency to have bone loss and thin bones is passed down through families.

Osteoporosis

A drop in estrogen in women at the time of menopause and a drop in testosterone in men is a leading cause of bone loss. Other causes of bone loss include:

• Being confined to a bed
• Certain medical conditions
• Taking certain medicines

Other risk factors include:

• Absence of menstrual periods (amenorrhea) for long periods of time
• A family history of osteoporosis
• Drinking a large amount of alcohol
• Low body weight
• Smoking

There are no symptoms in the early stages of osteoporosis. Many times, people will have a fracture before learning that they have the disease.

Pain almost anywhere in the spine can be caused by fractures of the bones of the spine. These are called compression fractures. They often occur without an injury. The pain occurs suddenly or slowly over time.

There can be a loss of height (as much as 6 inches) over time. A stooped posture or kyphosis (also called a dowager's hump) may develop.

Bone mineral density testing (most often with a DEXA scan) measures your bone mineral density. Your health care provider uses this test to:

• Diagnose bone loss and osteoporosis
• Predict your risk of future bone fractures
• See how well osteoporosis medicine is working

A spine or hip x-ray may show fracture or collapse of the spinal bones. However, simple x-rays of other bones are not very accurate in predicting whether you are likely to have osteoporosis.

You may need other blood and urine tests if your osteoporosis is thought to be due to a medical condition, rather than simply the usual bone loss seen with older age.

Medicines to treat osteoporosis can help prevent future fractures. But spine bones that have already collapsed cannot be reversed.

Osteoporosis can cause a person to become disabled from weakened bones. Hip fractures are one of the main reasons people are admitted to nursing homes.

Calcium is important for building and maintaining healthy bone. Vitamin D is also needed because it helps your body absorb calcium. Following a healthy, well-balanced diet can help you get these and other important nutrients.

Other tips for prevention:

• Do not drink large amounts of alcohol.
• Do not smoke.
• Get regular exercise.

Medicines can prevent osteoporosis. Your doctor can tell you if any are right for you.

Lewiecki EM. In the clinic. Osteoporosis. Ann Intern Med. 2011;155(1):ITC1-1-15;quiz ITC1-16.

National Osteoporosis Foundation. Clinician's Guide to Prevention and Treatment of Osteoporosis. Washington, DC: National Osteoporosis Foundation; 2010.

North American Menopause Society. Management of osteoporosis in postmenopausal women: 2010 position statement of The North American Menopause Society. Menopause. 2010 Jan-Feb;17(1):25-54.

Park-Wyllie LY, Mamdani MM, Juurlink DN, Hawker GA, Gunraj N, Austin PC, et al. Bisphosphonate use and the risk of subtrochanteric or femoral shaft fractures in older women. JAMA. 2011;305(8):783-789.