Bone mineral density (BMD) is the mass of bone mineral per volume of bone tissue. A BMD test, also known as a bone mass measurement test, is used to gauge a person's risk of developing osteoporosis and bone fracture. Read on to learn more about BMD and the benefits and risks of getting a BMD test.
What is a Bone Mineral Density Test?
There are many types of BMD tests, with all of them being non-invasive. The tests differ primarily in which bones are measured to gauge the person's BMD. The most common BMD test used in hospitals and clinics is a central dual-energy x-ray absorptiometry (DXA) test, which measures the bones of the hip and lumbar spine. If these bones are inaccessible, the bones of the forearm and heel may be used instead. The process is painless and requires low exposure to radiation, much like a standard x-ray.
The results are then compared with the mean BMD value for a healthy young adult, often a 30-year-old of the same sex and ethnicity. A significant deviation from the mean may indicate that the person is at risk of developing fractures and osteoporosis.
For a more detailed explanation of how a BMD Test is scored, click here.
Why Measure BMD?
Numerous studies show a strong correlation between low BMD and risk of bone fracture. Falls resulting in fractures of the pelvis and leg bones are a major cause of injury for older people, especially post-menopausal women. The cost of treatment and potential disability can be life-altering. A BMD test can detect low BMD before a fracture occurs. The doctor can then recommend medication and/or lifestyle changes to increase BMD. Repeated BMD tests are usually performed every 1-2 years to monitor changes in the person's BMD in response to osteoporosis medication, changes to diet, and/or physical activity.
Who Should Get a BMD Test?
The U.S. Preventive Services Task Force recommends that women age 65 and older get a BMD test. Similarly, the National Osteoporosis Foundation (NOF) recommends a BMD test for the following groups of people:
- Women aged 65 and older
- Men aged 70 and older
- People older than 50 who break a bone
- Menopausal or post-menopausal women with risk factors as determined by a clinical assessment tool
- Men ages 50-69 with risk factors as determined by a clinical assessment tool
Osteopenia vs. Osteoporosis
Low BMD that isn't severe enough to be osteoporosis is often diagnosed as osteopenia, a risk factor for osteoporosis. A below-average BMD value that doesn't meet the threshold for osteopenia may be attributed to hereditary factors and can usually be addressed with small lifestyle changes. While many people with low BMD live healthy lives without fractures or osteoporosis, it doesn't hurt to take precautions.
The information provided by a BMD test can help your doctor decide which prevention or treatment options are right for you.
Many factors can contribute to low BMD, including:
- Hereditary factors
- Malnourishment, especially during childhood
- Height loss in older individuals
- Low body weight
- Use of medication that weakens bone, such as corticosteroids
- Smoking and drinking
- Vitamin D deficiency
Can You Increase BMD?
In most cases, low BMD can be corrected or addressed by slowing the rate of bone loss and giving the body what it needs to support bone growth. A doctor may recommend regular exercise, such as walking, jogging, and weight training. Carrying moderate to heavy loads and allowing your bones to undergo impact (e.g., while jogging), causes your bones to adapt and become stronger and more resilient.
Eating a balanced diet with foods high in calcium and vitamin D is crucial. Examples include leafy green vegetable
s, dairy products such as milk, cheese, and yogurt, and certain fish including salmon and sardines. Collagen, protein, and magnesium also promote calcium and vitamin D absorption. Calcium and vitamin D supplements are another option.
Equally important is avoiding stressors such as cigarette smoke, alcohol, sugar, and caffeine. Consuming too few calories can also reduce BMD.
If you have or are at risk of developing osteoporosis, talk to your doctor to get a personalized treatment plan. Follow your doctor's advice on whether you should take supplementary BMD tests.