Bone Density Test: When Do I Need One?

You may have heard of osteoporosis. It is a bone disorder that mostly affects older people, usually older women. It is characterized by weaker bones that are susceptible to fractures and falls. It is expected that the prevention of this disease begins in childhood, especially in those that have a family history of osteoporosis or are at a higher risk.

Regardless of whether or not one prevented its onset or occurrence as a child, a bone density test is important. It is especially advised for people who are at a greater risk of developing osteoporosis. This is because osteoporosis is a silent condition, where you don’t feel any symptoms.

What is a bone density test?

A bone density test is a procedure carried out to measure the strength of your bones. It is called a DXA (dual-energy x‐ray absorptiometry) scan; a kind of x‐ray that determines if you have osteoporosis. The X-rays measure the amount of calcium in grams and other bone minerals packed into a segment of a bone.

Previously, osteoporosis could only be suspected and diagnosed after breaking a bone. Often time, it would have already been late and your bones, way weaker. A bone density test increases the accuracy of calculating your risk of having fractures.

Young Caucasian medical technician operating the bone densitometer while his patient is lying on the bed.

The bone density test is usually a preventive measure to find and treat severe bone loss and prevent fractures and disability. It is done within a few years. The bones that are often tested are in the spine, hip, and sometimes the forearm.

What can a bone test do?

A bone density test informs you about the state of your bone. It lets you and your healthcare provider know whether or not you have normal bone density. It also indicates if you have low bone density (osteopenia), or osteoporosis. At the moment, it is the only test that can diagnose osteoporosis. A bone density test can help you and your healthcare provider with the following:

  • Know your bone density status before you break a bone. It lets you know if you have mild bone loss (osteopenia) or serious bone loss (osteoporosis).
  • Determine your risk of breaking a bone (or having a fracture) in the future.
  • See if your bone density is still the same over time, improving or deteriorating.
  • Discover or rate how well an osteoporosis medication is working. It is used to monitor osteoporosis treatment.
  • Diagnose if you have osteoporosis after you have a fracture.

Who should get a bone density test?

The following set of people should get a bone density test:

  • Women aged 65 and above
  • Men aged 70 and above
  • People who broke a bone after age 50
  • Postmenopausal women aged 50 and above
  • Menopausal women with risk factors
  • Men aged 50‐69 with risk factors

Doctor talking to senior patient prior to bone density measurement in radiology

Risk factors include:

  • Having rheumatoid arthritis
  • Smoking
  • Heavy alcohol consumption
  • Low body weight
  • Use of certain medications such as steroid medications.
  • Having fracture in an accident
You may also be recommended to have a test for the following reasons:
  • X‐ray. If an x‐ray of your spine shows a fracture or bone loss in your spine, you may need a test.
  • Lost height. People who have lost more than half an inch in their original height within a year may need the test. This is because they may have compression fractures in their spines, which may result from osteoporosis.
  • Fractures. If you sustain fractures or break bones after minor accidents, your bones may be very fragile.
  • Certain medications. Prolonged use of medications such as steroid medications can result in osteoporosis. This is because they interfere with the bone‐rebuilding process. Examples of these drugs are prednisone, cortisone, etc.
  • Transplant. People who have undergone organ or bone marrow transplants are at a higher risk of osteoporosis. This is usually as a result of the anti‐rejection drugs administered to such people. They also interfere with the bone‐rebuilding process.
  • A decrease in hormone levels. A drop in levels of hormones such as estrogen and testosterone can result in weaker bones. Certain cancer treatments can result in this.
  • Back pain. If you are having back pain without a cause, you may need a test.

What to expect?

The bone density test usually checks and tests the bones in your spine, hip and forearm. They are more susceptible to fractures when you have osteoporosis.

Female doctor examining woman in 40s at Bone Densitometer Machine

There are two types of bone density tests. They include:

Central DXA

This test is for your spine and hip bones and lasts about 10 minutes. It gives more accurate results. However, it is more expensive.

During the test, you will be requested to lie down on a padded platform, fully clothed. A machine that sends low doses of x‐rays into your body is allowed to pass over you. Once done, it comes up with an image of your skeleton. The results are shown as to how the x‐rays change after passing through your bones. They are read and interpreted by an expert.

Peripheral Test

As its name implies, this test measures the bone density at your wrist, finger, and heel. It is less accurate and precise than the central DXA. However, it is usually cheaper. The device used is compact and portable, making the test available to more people, especially those who can’t access the central DXA test.

When do I need a bone density test?

It is advisable if you are at a higher risk of developing osteoporosis to get the test done. This may include undergoing cancer treatments or organ transplants, using certain medications such as steroids, and such as outlined earlier. You may be asked to have a repeat test every 1 to 2 years.

What do your results mean?

Medical woman explaining why to do a bone mineral density (BMD) test

After your bone density test, you’ll get 2 scores namely:

  • T score. This score is gotten from comparing your bone density with that of a healthy, young adult of your sex. The score shows whether your bone density is normal, below normal, or at levels that indicate osteoporosis.

    Values from minus 1(‐1) and above indicate normal bone density. Values from ‐1 to ‐2.5 mean your bone density is low and you are at risk for osteoporosis. Values from ‐2.5 and below mean you have osteoporosis.

  • Z score. This score is gotten by comparing how much bone mass you have with other people of your age, sex, weight, ethnicity, or race.

    A Z‐score below ‐2.0 indicates having less bone mass than someone of your age. It also tells you and your healthcare provider that your less bone mass is caused by something asides from aging.


Prevention, they say is better than cure. Once again, it is advised to have a bone mineral test as soon as you notice the risk factors of osteoporosis.

Having low bone density doesn’t mean you will develop osteoporosis. It only means you have a higher chance of having it later on in life if not well managed. Thus, having the test done early as a preventive measure is best.



Bone Density Exam/Testing. National Osteoporosis Foundation Web Site. Retrieved from:

Bone Density Test. MayoClinic Website. Retrieved from

Bone Density Tests: When you need them and when you don’t. Choosing Wisely Canada Website. Retrieved from:

How it is performed: Bone density scan (DEXA scan)(2019). NHS Website. Retrieved from:

What is a Bone Mineral Density Test? WebMD Website. Retrieved from:

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