Fragile Bones
Osteoporosis is a disease of bone fragility. It can result in fractures because of low bone mass and deterioration of the architecture and strength of bone tissue. In the United States alone, more than 1.8 million fractures occur annually due to osteoporosis.
The first indication of osteoporosis may be an acute fracture, often of the wrist, spine or hip. Osteoporosis is a “silent disease,” and it may cause multiple and relatively painless spinal fractures that result in a loss of height and a curvature of the spine called the Dowager’s Hump. Early detection and treatment of patients who have low bone mass can prevent many of these fractures.
As We Age
Decrease in bone mass occurs as people age. Peak bone mass occurs between the ages of 30 and 35. After this age, about 1% of bone calcium is lost per year. In women, menopause (natural or surgical) and the loss of estrogen accelerate the calcium loss at 4% to 6% per year for about a six-year period. The loss of estrogen is the reason women are more prone to osteoporosis than men. Men have a similar, but smaller, loss of testosterone, which can also accelerate the loss of calcium.
Other factors that can contribute to the development of low bone mass include poor nutritional intake of calcium and vitamin D, mal-absorption conditions, endocrine and renal medical problems, use of medications that interfere with calcium absorption, excessive alcohol or tobacco usage, sedentary lifestyles, medical conditions that prevent weight-bearing activities, and hereditary influences.
The T-Score
Diagnosis of low bone mass is best achieved by a central DEXA (dual energy x-ray absortiometry) scan, a type of bone density technology that measures the calcium content of bone at various sites (usually the spine, hip or forearm). The amount of calcium measured at a specific site is compared to peak bone mass, which is obtained between the ages of 30 and 35. A value is assigned to this measurement called a “T-score,” which relates the amount of calcium lost compared to peak bone mass.
A T-score of -1.0 (less than 10% loss of calcium) is normal; a T-score between -1.0 and -2.0 (11% to 25% loss of calcium) is termed osteopenia; and a T-score more than -2.5 (more than 25% loss of calcium) is termed osteoporosis. A repeat DEXA scan, usually done at one to two year intervals, can be performed to detect changes in the T-score or monitor the effects of therapy.
Diagnosis of osteoporosis requires a measurement of bone mass, such as a DEXA scan, and an evaluation fro medical conditions that may cause low bone mass or interfere with treatment. This evaluation requires an overall assessment of an individual’s health status and may include laboratory and x-ray studies.
Take That Calcium
Prevention of low bone mass includes adequate calcium and vitamin D intake. Supplement calcium is generally necessary to achieve the appropriate amount (children 500 mg per day and adults 1,000 mg per day). Vitamin D metabolism depends on adequate intake as well as sunlight exposure. Vitamin D supplements of 400 to 800 units daily are recommended.
Lifestyle measures are important in bone metabolism and include participation in weight-bearing activities or exercise, avoidance of excessive alcohol and tobacco usage, and treatment of medical conditions that influence bone metabolism.
Persons with a loss of 15% (T-score -1.5) or more are at increased risk of future fractures. The National Osteoporosis Foundation’s Risk Assessment Study found that 90% of eventual fractures occurred in patients who had calcium loss of 15% or more.
The best diagnostic test to assess the potential of a future fracture from low bone mass is the central DEXA scan. The person at most risk for a fracture is one who has had a recent fracture. More than 20% of this group will have an additional fracture within one year.
Lifestyle Strategies
Strategies to prevent fractures include “fall-proofing” the home, use of assistance devices (canes, rails on stairs, and so forth), “hip protectors,” limiting medications that interfere with alertness and coordination, exercise programs, and instruction in “how to fall.” All these measures can be helpful in preventing fractures.
Medications
Medications to treat low bone mass are generally recommended when the calcium loss exceeds 15% (as measured by DEXA). Treatment involves the use of supplemental calcium (1,000 to 1,500 mg daily) and Vitamin D (400 to 600 units daily), along with additional medications to help incorporate the calcium into the bones.
Low bone mass and the fractures it can cause are a national health concern. Deterioration in quality of life, with loss of ambulation and the ability to live independently, is often the result of many of these fractures. Awareness, prevention, early detection and treatment can alter the devastating effects of this problem.
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