What Is a Bone Density Test?

Bones undergo a constant process of building and repair. On top of this, many factors affect its growth and breakdown. For example, poor nutrition, lack of exercise, disease and medications can increase bone loss and reduce bone repair. These lead to loss of bone density which causes weakening of bones or osteoporosis. In the United States, osteoporosis causes about 1.5 million fractures each year. To determine if you are at risk for osteoporosis, your doctor may recommend a bone density test.

What Is a Bone Density Test?

This test measures the amount of mass and the degree of solidness of your spine, hip and wrist bones. These are the bones which are commonly fractured when you develop osteoporosis. Some tests also measure bone density in the heel or the hand. A bone density test is a painless and safe way to determine if you are suffering from loss of bone mass with the use of X-ray technology.

Doctors may recommend a bone mineral density test for the following reasons:

  • Ÿ   To detect decreased bone density or osteopenia which increases your risk for fractures
  • Ÿ   To confirm diagnosis of osteoporosis in a person who sustained a fracture
  • Ÿ   To predict a person’s risk of having a fracture
  • Ÿ   To determine your rate of bone loss
  • Ÿ   To monitor the effects of bone treatment

Types of Bone Density Tests

To further understand the question of "what is a bone density test", let us learn more about the different types of machines that can test for bone density. The machines that measure mineral density of bones in your spine, hip and whole body are called "central" machines while the ones measure density in the fingers, wrists, kneecaps, shinbones and heels are called "peripheral" machines. Here are some types of tests for bone density:

  • Ÿ   Dual Energy X-ray Absorptiometry (DXA) - for the spine, hips or whole body.
  • Ÿ   Peripheral Dual Energy X-ray Absorptiometry (pDXA) - for the wrists or heels.
  • Ÿ   Single Energy X-ray Absorptiometry (SXA) - for the wrists or heels.
  • Ÿ   Quantitative Ultrasound (QUS) - sound waves that measure bone density at the heels.
  • Ÿ   Quantitative Computed Tomography (QCT) - commonly used for the spine.
  • Ÿ   Peripheral Quantitative Computed Tomography (pQCT) - commonly used for the wrist.
  • Ÿ   Radiographic Absorptiometry (RA) - uses X-ray for the hand.

How Much Does a Bone Density Test Cost?

If you are not covered by health insurance, a bone density test may cost about $150-$250, including consultation with a doctor to explain your results.

If you are at risk of osteoporosis (usually elderly individuals) and covered by Medicare and some private health insurance, you may consider an out-of-pocket cost or a co-pay of $10-$30 or a coinsurance of 10-40% of the total amount.

Should You Get a Bone Density Test?

If your doctor recommends you get this test, you may want to ask him "what is a bone density test?" He will also explain to you why you need it. In most cases, it is part of a preventative screening procedure done to individuals who are at high risk of developing osteoporosis. According to the National Institutes of Health, people who should get preventative screening for bone mineral density includes:

  • All women older than 65
  • Women over the age of 60 who have a high risk of osteoporosis
  • Men over the age of 70
  • Patients taking steroid medications for at least 2 months (for autoimmune disorders)

Factors that increase your risk for osteoporosis include:

  • Smoking
  • Chronic kidney disorder
  • Early menopause
  • Eating disorder
  • Family history of osteoporosis
  • Fractures sustained from doing regular activities (fragile bones)
  • Regular consumption of alcohol (at least 3 drinks/day)
  • Rheumatoid arthritis
  • Significant loss of height (compression fracture of the spine)

What Can You Expect in a Bone Density Test?

1. Central Device Test

You will lie on your back while a mechanical measuring device passes over your body. This procedure involves a low amount of radiation (much less exposure than a chest X-ray) and takes only about 10 - 30 minutes.

2. Peripheral Device Test

Another way of testing for bone density is by using a small, portable device that can measure bone mineral density in your fingers, wrists or heels. The test is less expensive than tests using central devices.


Bone mineral density may vary from one bone to another and the measurements taken at the heels are usually not as accurate as those taken at the spine or hips. If you test positive for osteoporosis on a peripheral device, your doctor may recommend a follow-up test at your hip or spine to confirm the diagnosis.

What Are the Possible Results of a Bone Density Test?

What is a bone density test result? There are basically three kinds of results which help predict if you are at risk for osteoporosis.

1. Normal Bone Density

A T-score of +1, 0 or -1 means that you have normal bone density and you do not need treatment. However, you need to take steps to preserve your bone health and prevent bone loss by taking adequate amounts of vitamin D, calcium and exercising regularly.

2. Low Bone Mass

A T-score between -1.1 and -2.4 means that you have low bone mass (or osteopenia). You are at risk of developing weak bones (osteoporosis) so you must take steps to prevent this by improving your diet and taking medications.

3. Osteoporosis

A T-score of -2.5 or less means that you have osteoporosis with a greater risk of fracturing your bones. You will be advised to take medications and may be placed on an exercise program to increase bone strength.

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