All about Bone Mineral Density & Bone Mineral Density Test

Medically Reviewed By : Dr K. Hari Chandana

MBBS, MS ORTHOPAEDICS
( Fellowship in Trauma, Fellowship in Pain Management )

Maintaining good bone health is essential for leading a healthy and active lifestyle. Bones not only provide support for our body but also protect vital organs. As we age, our bones naturally become weaker and more susceptible to fractures and breaks. Conditions like osteoporosis can occur due to low bone mineral density.

Thus, it becomes important to ensure that our bones are getting the necessary nutrients and exercise to maintain healthy bone mineral density levels.

You might be less familiar with the term bone mineral density, and why not? We don’t use it so often. Lap through this article to understand what the term bone density means and what tests can help you understand your bone health scores.

In This Section

What is bone mineral density?

Bones are made up of minerals like calcium and phosphorus. Bones are not hollow, they are dense and solid because of the these minerals. So it is called bone mineral density.

Normal mineral bone density means that the right amount of minerals fill a particular piece of bone. Depending upon this equation, the T-score means the bone is dense if the proportion of minerals is filled in the right amount, up to 30 years of age. This T-score should be in the +1 to -1 range.

If it goes below -1 to -2.5, it is low bone mineral density and if it goes below -2.5, then it is diagnosed as osteoporosis.

The prevalence of low mineral density is much higher than osteoporosis. Eventually, if preventive measures are not taken, low mineral density bones suffer from osteoporosis and are prone to fractures.

What are the causes of low BMD:

Low bone mineral density is also called osteopenia which is not severe enough to call it osteoporosis, its an alarming that it needs remedial, preventive measures.

As an aging process, it's common to lose minerals. Minerals go on decreasing at the level where the bone becomes low in density thus becoming weak, brittle, and prone to fracture.
Smoking, drinking alcohol can also cause bones to lose minerals. It affects the metabolism, thus causing less absorption of minerals by bones.
Poor diet and lack of intake of nutrition and vitamins and minerals can cause deficiency.
Inactivity can also cause poor absorption of minerals by bones thus decreasing bone mineral density
Hormonal imbalance, in menopause, lack of estrogen causes loss of minerals and bone cells.
Cancer is another cause, types of cancer cause bone loss and mineral loss, causing low BMD
The hyperactive parathyroid gland is also responsible for low BMD as it cannot make calcium available for the bone.

How low bone mineral density is diagnosed?

Low bone mineral density is diagnosed with the bone mineral density test.

What is it?

It is a test carried out to diagnose patients with osteoporosis and those with low bone mineral density prone to fracture.

It measures the amount of minerals contained in the bone. If the amount is higher, the bone is said to be strong and dense. If less amount of minerals is detected the bone is weaker and prone to fracture.

It can also diagnose whether treatment received by the patient of osteoporosis is effective or not and whether medications are working to prevent bones from fracture.

Bone mineral density is measured by central dual-energy X-ray absorptiometry. DXA also called Dexa scan. It measures the mineral density of major bones like the hip and spine and also peripheral joints like the hands , feet, heels, and wrists.

Another bone mineral density test is Quantitative ultrasound of the heels. It is an ultrasound of bones that visualizes broken bones, fractures, and osteoporosis.

But it is not reliable to detect whether the treatment of osteoporosis is effective or not. As it does not measures mineral bone density, it can’t detect the medicinal reaction in bones.

It is to test bone mineral density, especially, peripheral bones like the wrist and heels. This test is not very accurate. If the results show changes in the bones of the heel or wrist, then doctors will ask to do a central DXA scan to confirm the diagnosis.

How do you interpret the results of a BMD test to determine if you are at risk?

The BMD test is difficult to interpret for non-medical people; some scores indicate your bone mineral density.

There are two scores for BMD

T-score:

T-score is obtained after comparing the normal bone mineral density results with the age group of old people, those beyond the age of 50, and post-menopausal women.
T-score interpretation: +1 is considered normal, with strong bones and good mineral density.
Less than -1 to -2.5 is considered low mineral bone density and carries a high risk of osteoporosis
A score below -2.5 is considered frank osteoporosis and severe loss of mineral bone density. Sometimes it is only diagnosed after the fracture of the bone. Z-score:
It is obtained by comparing the normal bone density results with the otherwise normal bone of the age group of people who are below 50, including post-menopausal women.

It also helps to compare results with children.

Interpretation: If the Z-score is -2 or less, it means osteoporosis. If you are taking treatment for osteoporosis, it can also help to predict the effectiveness of the treatment.

Who is recommended to do the BMD test?

What you need to do before the BMD test:

Contraindications to BMD:

Conclusion

A bone mineral density test is interpreted by doctors to rule out the diagnosis. After the test is carried out, one must seek the opinion of the doctor for interpretation and proper treatment follow-up.