If you have concerns about the strength of your bones or the possibility of sustaining fractures due to osteoporosis, then a bone density test can tell you if your bones are at the normal strength. Read on to learn more about the testing.
A bone density test is also known as densitometry or a DEXA scan. The purpose of a bone density test is to see if you have osteoporosis or if you are at risk of getting osteoporosis before any bones are broken. Be aware that a bone density test is not the same as a bone scan. Bone scans are carried out to see if you have any fractures, cancer, infections or other abnormalities in your bones. An injection is used beforehand. No injections are used with bone density scans. The bone density test can tell you if you have a lower bone density than you should but it cannot tell you why, so if you do have a lower bone density, your doctor will carry out a complete evaluation in order to find the cause.
Bone density testing uses special x-rays in order to measure the amount of calcium and other bone minerals that are in a segment of bone. The higher the mineral content, the denser your bones are. Denser bones are stronger and less likely to break. The test is done on the bones that are most likely to break due to osteoporosis – such as the lumbar vertebrae, the femur, and the wrists and forearm.
Bone density testing can be done using central or peripheral devices. Central devices use large machines that you lie down on while peripheral devices use small machines that measure the bone density on an outer part of your skeleton such as the heel or finger. Central devices include a DEXA scan and a quantitative CT scan.
The test results are given in two different numbers – the t-score and the z-score. The t-score is the bone density compared to what is normal in a healthy young adult of your gender. If your score is above -1, you have normal bone density. If it is between -1 and -2.5, your bone density is below normal and may result in osteoporosis. If it is below -2.5, you have osteoporosis. The z-score is the number of standard deviations above or below what is generally seen in someone of your age, sex, weight, and racial origin. This can be helpful as it can indicate if you have a secondary form of osteoporosis through which something else besides ageing is causing bone loss.
Bone density testing is fast, easy, painless, and non-invasive. In fact, you can get simple tests done at your local pharmacy. However, if you are having a test, be sure to tell the doctor if you have had a test that required oral contrast or nuclear medicine. This is because these tests use an injection that may interfere with the results of your test.
Bone density testing should be routinely undertaken by women that are 65 years or older or by people that are over 60 and have a higher risk of osteoporosis. However, you can have a bone density test at any age if you suspect that you are at risk of osteoporosis. Tests should be done every two years but your doctor will recommend the appropriate interval based on your personal history and risk factors. You should also have a bone density test done if you have been on hormone replacement therapy for long periods.