Men and women over 60 years of age are at higher risk of osteoporosis than younger people.
Nevertheless, it’s possible to have osteopenia (low bone mass) or osteoporosis at a much earlier age. As osteoporosis has no obvious symptoms, it's important to go to your doctor if any of the risk factors apply to you.
Your doctor will take a thorough medical history that includes information on any recent fractures and your current risk factors.
The next step may be to have a bone mineral density (BMD) or DXA test.
What is a BMD test?
Traditional X-rays can’t measure bone density, but they can identify spine/other fractures. Bone mineral density has to be measured by more specialised techniques. A number of different types of BMD tests are available, but the most commonly used is DXA (dual-energy X-ray absorptiometry).
DXA is a low-radiation X-ray capable of detecting quite small percentages of bone loss. It’s used to measure spine and hip bone density, and can also measure bone density of the whole skeleton.
A DXA scan, which is used to measure spine and hip bone density, is the most common technique for assessing the risk of osteoporosis as well as follow-up treatment.
There are also a number of other types of tests:
- DPA (dual photon absorptiometry) measures the spine, hip or total body.
- SPA (single photon absorptiometry) measures the wrist.
- QCT (quantitative computed tomography) measures the spine or hip.
- PQCT (peripheral QCT) measures the forearm.
- QUS (quantitative ultrasound) uses sound waves to measure the heel, tibia or finger.
What do my test results mean?
The World Health Organization has defined a number of threshold values (measurements) for osteoporosis. The reference measurement is derived from bone density measurements in a population of healthy young adults (called a T-score). Osteoporosis is diagnosed when a person’s BMD is equal to or more than 2.5 standard deviations below this reference measurement.
Osteopenia (low bone mass) is diagnosed when the measurement is between 1 and 2.5 standard deviations below the young adult reference measurement.
The test results can be summarised as follows:
Bone mineral density (BMD) score
T-score of -1 or above
T-score lower than -1 and greater than -2.5
T-score of -2.5 or lower
T-score of -2.5 or lower, and presence of at least one fragility fracture
If the results of your BMD test show osteopenia or osteoporosis, it doesn’t automatically mean that you will have a fracture. Your doctor might prescribe lifestyle changes and other therapies to slow down bone loss and help prevent fractures.
TAKE NOTE: A bone density test is one of the methods used to determine your future risk for fracture. A vast majority of osteoporotic fractures occur in the normal to osteopenic bone-density range.
Other methods for diagnosing osteoporosis
A number of other methods have been used extensively in clinical trials and epidemiological studies to diagnose osteoporosis. These include radiological assessments and certain blood and urine tests that look for Bone Turnover Markers (BTM).
These tests reveal whether there’s an increased rate of bone turnover, which may suggest osteoporosis.
Reviewed by Teréza Hough, CEO of the National Osteoporosis Foundation of South Africa: www.osteoporosis.org.za. October 2017.