Bone density test
What is a bone density test?
A bone density test measures the levels of calcium and other essential minerals in your bones. Otherwise known as the bone mineral density test, it evaluates how porous the bones are. The dual energy x-ray absorptiometry (DEXA) is considered to be the most precise as it is able to detect changes as low as 1%.
Why is it conducted?
Some bone loss as one ages is expected, but certain factors contribute to remarkable bone loss at a much earlier age. This can lead to debilitating fractures of the hips or of spinal bones that sharply reduce your mobility. Besides, it can even cause sudden fractures without any forceful impact, therefore making it very difficult the sufferer to lead a normal and pain free life.
As the bone density test helps to determine the onset of osteoporosis, it is useful to work out if any preventive care is needed. It helps to know the likelihood of fractures in the future as it gauges the degree of bone loss. However, it cannot be considered the only factor responsible for fractures. As such it can also be used as a guide to judge the efficacy of osteoporosis treatment.
Who should go for it?
- The general advice is for women over 65 as a drop in estrogen at menopause accelerates bone loss. Women with early menopause are advised to go for the test much earlier.
- Men over 70 should have this test as a drop in testosterone contributes to thinner bones.
- There are certain conditions where it is considered advisable such as liver and kidney disease, diabetes, malnutrition, hyperparathyroidism, IBS and so on.
- Those indulging in excessive alcohol consumption or tobacco use.
- Steroids used for the treatment of various diseases also cause bone erosion, so people who take steroids on a long term basis should undergo this test.
- Anti cancer treatment, proton pump inhibitors, some anti depressants (SSRI) are also said to be detrimental for bones.
- A person who has had a fracture on slight impact should have this test.
This is a non invasive test wherein a scanner is passed over the body. It lasts approximately 10 minutes and is absolutely pain free. It may be a central scan where your spine and hip is scanned or in a peripheral scan parts of your arm or leg may be scanned. The central test is considered to be more accurate.
Interpretation of results
The test results for DEXA are presented as T-scores and Z-scores.
- T-scores: This compares your bone density to that of the peak density for your gender. Whereas a T-score between +1 and – 1 lies within the normal deviations, scores between -1 to -2.5 are of concern and indicate osteopenia. T-scores that are -2.5 or lower are definitely indicative of osteoporosis.
- Z-scores: This is a comparison of your scores with that of people within the same age, weight and ethnicity. This can help to highlight the possibility of extraneous factors affecting bone loss other than osteoporosis. If a Z-score is less than -1.5 then other underlying factors need to be treated as well.
Written by: Nandita tripati
Date last updated: January 07, 2015