A bone-density test gives out a small amount of radiation, but radiation exposure can add up.
A bone-density scan is a way to measure the strength of your bones. The test, called a DEXA scan, is a kind of X-ray. The main reason to have the test is to find and treat serious bone loss, called osteoporosis, and prevent fractures and disability.
A DEXA scan measures the mineral density of the bone, usually in the hip and spine. Results are given as a “T-score”, which is your bone density compared with a normal young adult of the same sex.
Most people under age 65 probably don't need the scan
Most people do not have serious bone loss.
Most people have no bone loss or have mild bone loss (called osteopenia). Their risk of breaking a bone is low so they do not need the test. They should exercise regularly and get plenty of calcium and vitamin D. This is the best way to prevent bone loss.
The bone-density scan has risks.
A bone-density scan gives out a small amount of radiation, but radiation exposure can add up. The effects can add up in your body over your life, so it is best to avoid it if you can.
Who should get a bone-density scan?
Women should get a DEXA scan at age 65, and men age 70 and up. They may want to talk with their health care providers about the risks and benefits before deciding. Younger women and men aged 50 to 69 should consider a scan if they have risk factors for serious bone loss. Common risk factors include:
Breaking a bone in a minor accident
Having rheumatoid arthritis
Having a parent who broke a hip
Smoking or drinking excess alcohol
Having a low body weight
Using corticosteroid drugs for three months or more.
Most changes in bone density do not happen quickly. There is often no benefit having a follow-up DEXA scan for at least 5 years. If your T score from your first scan was 2.00 or more, you do not need another scan for 5 years. You may need a follow-up scan sooner if you have risk factors for bone loss, such as:
Hyperparathyroidism (where your parathyroid gland is over-active)
Taking certain medicines, such as steroids, or hormones for treating breast or prostate cancer
Low levels of vitamin D
How can you keep your bones strong?
The following steps can help you build bone:
Exercise. The best exercise for your bones is exercise that makes your bones carry weight. When you walk, your bones carry the weight of your whole body. You can also lift weights. Aim for at least 30 minutes of weight-bearing exercise a day.
Get enough calcium and vitamin D. They help keep your bones strong. Aim for at least 1200mg of calcium a day. Eat foods high in calcium, such as dairy products, leafy green vegetables, and canned sardines and salmon.
Avoid smoking and limit alcohol. Among other things, smoking and drinking alcohol can speed up bone loss. Quitting smoking can be difficult, but there are many treatments that can help you do it. Ask your healthcare provider or contact Quitline on 0800 778 778. For alcohol, limit yourself to one drink a day for women, and two drinks a day for men.
Try to avoid certain medicines. Some medicines can damage bones. These include proton pump inhibitors (such as omeprazole, lansoprazole, and pantoprazole) used to treat heartburn; corticosteroids; and some of the newer antidepressants. If you take one of these medicines, ask your healthcare provider about whether these medications are right for you.
It's OK to ask questions
If you have questions about your symptoms or the medicines managing your symptoms, speak with your health professional.
Developed by Choosing Wisely New Zealand, 2018. Adapted from Choosing Wisely Canada and Choosing Wisely USA/Consumer Reports (2016) “Bone density tests: when you need them and when you don’t” and BPAC New Zealand (2008) “Prevention of Osteoporosis”. Choosing Wisely does not assume any responsibility or liability arising from any error or omission or from the use of any information in these resources.
This article is part of our content on Choosing Wisely, a campaign encouraging a change in thinking by health professionals and consumers to avoid unnecessary medical intervention.