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A bone density test, sometimes also referred to as a bone mineral density test ascertains whether you have osteoporosis or not. Osteoporosis is a medical condition that leads to weaker and fragile bones, mostly because of deficiency of calcium/vitamin D or hormonal changes.
How does a bone density test work?
The bone density test is a quick and pain-free test that uses x-rays to determine the density or thickness of your bones. The test measures the concentration of minerals and calcium in your bones. If you have higher minerals, it means your bones are denser, stronger, and not likely to break on an impact. On the contrary, if you have lower minerals, it means you have a greater risk of fractures and broken bones.
What to expect from a bone density test?
A bone density test is usually carried out for the bones in your forearm, spine, and hip as they are more vulnerable to breaking if you have osteoporosis. Generally, there are two types of bone density tests:
Central DXA: Central DXA stands for Dual Energy X-ray Absorptiometry, and it takes a look at your hip bones and spine. While it may cost a tad bit more than the other test, it has a tendency of being more accurate. In the central DXA test, you would have to rest on a padded platform, and a machine would pass over you, emitting x-rays through your bones. It gives a picture of your entire skeleton, which is interpreted by a doctor to determine whether you have osteoporosis or not.
Peripheral Test: The peripheral test is used to find out the bone density of fingers, heels, and wrists. It is usually cheaper as it is not thorough and doesn’t examine the bones in the hips or spine. However, the device through which the test is carried out is portable, which means it is more accessible for those who might not be able to get a central DXA test.
How to prepare for a bone density test?
While bone density tests are virtually pain-free, quick, and easy, there are a few things you need to keep in mind:
- Don’t take calcium supplements for at least 24 hours before taking a bone density test, as it could interfere with the results.
- Ensure to wear comfortable and loose clothing on the day of the test and avoid apparel with buttons, zippers, and belts.
- In case you have had an injection of contrast dye or barium for an MRI or a CT scan, wait for at least a week before going for a central DXA. This is because the contrast dye could hinder the results of the bone density test.
How to interpret bone density test results?
A bone density test gives two scores to help determine whether you have osteoporosis or not. They are: T score: The T score compares your bone density with that of a young and healthy adult of your gender. It helps to find out whether your bone density is normal, low, or at that level which indicates osteoporosis. Here are the different ranges of T score:
- -1 and above: Normal bone density
- -1 to -2.5: Low bone density and might lead to osteoporosis
- -2.5 and above: Osteoporosis
Z score: The Z score enables you to perform a comparison between your bone mass and of other people of your size, age, and gender. A Z score that is below -2.0 indicates that you have lesser bone mass in comparison to other people that fall in your age group, and it could be the result of some other underlying condition other than ageing.
Who should get a bone density test?
While osteoporosis is most common amongst women, it can also occur in men and its risk increases as you age. Before opting for a bone density test, you must consult with your doctor, and they might prescribe you a bone density test if you:
- Are a woman nearing 65
- Break a bone after 50
- Have lost 1.5 inches or more of your height
- Have back pain without any reasonable explanation
- Have a drop in hormone levels
To Conclude: A bone density test is used to detect whether you have osteoporosis or not, a condition that makes your bones brittle, fragile, and weak. It uses x-rays to find out the concentration of calcium in your bones and comes in two types - the central DXA test and peripheral test. You can interpret the results of your bone density test by familiarizing yourself with the T score and Z score. The risks in taking a bone density test are next to nothing as you are exposed to minimal levels of radiation, lower than that of an airplane flight or a chest x-ray.