Bone Mineral Density Scan (BMD, BMD Scan, Bone Mineral Density, Bone Mineral Density Test, Bone Densitometry)
Bone scan test results.
Bone scan test results.
The basics

A bone mineral density (BMD) scan is a test that uses X-rays to measure how much calcium and other minerals are contained in a segment of bone. It is used by doctors for a number of purposes, including:

  • assessing your risk for fractures
  • diagnosing osteoporosis (a condition where the bone becomes less dense and fragile)
  • monitoring progress or treatment of osteoporosis

Your doctor will determine if you need to undergo a BMD. In general, a BMD scan may be recommended if you:

  • are being treated for osteoporosis
  • are 65 years or older
  • are 50 to 64 years old and have risk factors for fracture or osteoporosis such as:
    • a fracture from a fall or bump
    • family history of osteoporosis or hip fracture
    • significant loss of height or weight
    • certain medical conditions that increase the risk of osteoporosis (such as rheumatoid arthritis)
    • treatment with steroids for a long time (more than 3 months)
    • taking medications that put you at a greater risk for osteoporosis and fractures
    • cigarette smoker
    • high alcohol intake
  • are under 50 and have certain risk factors for fracture or osteoporosis, such as:
    • a fracture from a fall or bump
    • been treated with steroids for a long time (more than 3 months)
    • taking medications that put you at a greater risk for osteoporosis and fractures
    • early menopause (before age 45)
    • certain medical conditions that increase the risk of osteoporosis (such as malabsorption syndrome, hyperparathyroidism)
Risks and precautions

The BMD scan is very safe. You will however be exposed to low levels of radiation and therefore this test is not recommended for pregnant women.

During the test

This test is normally done in a hospital, a diagnostic centre, or a doctor's office by a technologist. It usually takes between 20 to 45 minutes.

This is a pain-free test. You will be lying on a table while a machine scans your bones and measures how much radiation they absorb. Usually at least two different bones (usually the hip and the spine) will be measured to produce a reliable BMD reading.

There are also portable machines that can measure the bone density of the wrist, fingers, leg, or heel. You may find these machines in pharmacies, but they are less reliable for predicting your risk of osteoporosis.

Before the test

It is important that you fully understand what the test involves beforehand. Ask your doctor to explain the risks, benefits, and drawbacks of the test, and don't be shy to probe further until you are comfortable with your doctor's responses.

Be sure to remove any jewellery or metals from your body since they can interfere with the scan. You should also tell your health care provider if you are pregnant or have had a recent medical procedure where a contrast dye was used. Contrast dyes used in medical tests can also interfere with the results of the BMD scan.

If you are taking any prescription or over-the-counter (non-prescription) medications, supplements, or herbal products, make sure you inform your doctor or pharmacist. Ask them whether it is necessary for you to stop taking any of these medications and products before the test. It is also important to tell them if you have allergies to certain medications, bandages, latex, or have other medical conditions.

After the test

You can resume your normal daily activities right after the test. Your BMD result will be reported in the forms of a T-score and Z-score.

A T-score compares your bone density to that of young healthy adults of your gender. It is measured in units of standard deviations (SD), or how far you are from the average. If your T-score is below -2.5, or 2.5 SD below normal, it indicates that you have osteoporosis. If your T-score is between -1 and -2.5, you have osteopenia, which means your bones are thinner than normal and you are at a higher risk of osteoporosis.

Another type of score, the Z-score compares your bone density to those of other people with the same age, gender, weight, and ethnic background as you. If your Z-score is -2 or lower, it might mean that there are causes other than aging and menopause that might be responsible for your bone loss. The Z-score, is sometimes used for women who have not gone through menopause yet, younger men, children, and teenagers. Because seniors generally have low bone mineral density, using the Z-score may be misleading.

Ask your doctor when you can expect your test results to be made available.

Your doctor may order additional tests or medications for you depending on the results.

Bone scan test results.
Bone scan test results.

Medical Disclaimer

The information provided is for Canadian residents only. The contents are for informational and educational purposes only and are not a substitute for medical advice, treatment and diagnosis. The information is meant to educate you on health related issues. Always discuss the information with your Physician or other qualified health care professional ("Physician") before acting on it. Never disregard or delay acting on any advice given to you by your Physician because of something you have read on this site. Always seek the advice of a Physician regarding any questions you have about your medical symptom(s), condition(s) and treatment(s).