Osteoporosis is the thinning of bone tissue and loss of bone density over time. It occurs when the body fails to form enough new bone, when too much old bone is reabsorbed by the body, or both. Osteoporosis is the most common type of bone disease.
Researchers estimate that about one out of five American women over the age of 50 have osteoporosis. It is particularly common in post-menopausal women. Hip, vertebral, and other bone fractures (broken bones) can occur because of osteoporosis.
The minerals calcium and phosphate are essential for normal bone formation. As the body ages, calcium and phosphate may be reabsorbed back into the body from the bones, which makes the bone tissue weaker. This can result in brittle, fragile bones that are more prone to fractures, even without injury.
Bone loss usually occurs gradually over years. Many times, people will only become aware of osteoporosis after they have suffered a bone fracture. By the time a fracture occurs, the disease may be in its advanced stages.
Causes of osteoporosis include:
- Post-menopausal state (and possibly low testosterone in men)
- Being confined to a bed (or prolonged immobility)
- Chronic rheumatoid arthritis, chronic kidney disease and eating disorders
- Taking corticosteroid medications (prednisone, methylprednisolone) every day for more than 3 months, or taking some anti-seizure medications
White women, especially those with a family history of osteoporosis, have a greater than average risk of developing osteoporosis. Other risk factors include:
- Absence of menstrual periods (amenorrhea) for long periods of time
- Drinking a large amount of alcohol
- Family history of osteoporosis
- History of hormone treatment for prostate cancer or breast cancer
- Low body weight
- Too little calcium in the diet
There are no symptoms in the early stages of osteoporosis. Symptoms occurring late in the disease include:
- Fractures with little or no trauma
- Loss of height (as much as 6 inches) over time
- Low back pain due to fractures of the vertebrae
- Neck pain due to fractures of the vertebrae
- Stooped posture or kyphosis, also called a "dowager's hump"
The following tests may be performed to diagnose osteoporosis:
- Bone mineral density testing, called densitometry or DEXA scan, measures how much bone a person has. Physicians use this test to predict the risk of bone fractures in the future.
- Quantitative computed tomography (QCT), a special type of spine CT that shows loss of bone mineral density, may be used in some cases.
- In severe cases of osteoporosis, a spine or hip X-ray may show fracture or collapse of the spinal bones. Simple X-rays of bones are not very accurate in predicting the likelihood of osteoporosis.
- Blood and urine tests can determine if osteoporosis is thought to be due to a medical condition, rather than simply the usual bone loss seen with older age.
The goals of osteoporosis treatment are to:
- Slow down or stop bone loss
- Prevent bone fractures with medicines that strengthen bone
- Minimize the risk of falls that might cause fractures
There are several different treatments for osteoporosis, including lifestyle changes and a variety of medications.