Bone Mineral Density Test

Bone Mineral Density (BMD) Test

What is the Bone Mineral Density Test?

Bone Mineral Density Test means is the measure of the number of minerals ( like calcium and phosphorus and other types ) contained in certain volumes of bone.

The name of the test which tells about bone health is called the bone density test in which it is investigated if you have osteoporosis. It is a medical condition in which the bones become weak and easily broken.


What are the techniques or methods used to measure bone mineral density?

The most accurate and common one is the DEXA scan which is used to measure the bone mineral density. This is measured in two ways.

    1. Central Dexa
    2. Peripheral Dexa


1. Central Dexa: This Scan machine test is used in the hip, spine, and total body. 

    • DXA: Dual-energy X-ray Absorptiometry, DXA. Doctors consider it the most accurate and reliable for checking bone density and used to measure the spine, hip, and total body.
    • OCT: Quantitative Computed Tomography. The reason for not opting for this test most often is because it is costly and delivers a lot of radiation. This usually measures the spine and other sites of the body too.

Peripheral Scan machine checks the finger, wrist, kneecap, shinbone, and heel. This can machine is a good option when DXA scans are not available in that place. Still, the best choice for screening for the peripheral part is the best. Peripheral Screening tests include :


2. Peripheral Dexa: This scan machine measures the fingers, wrist, kneecap, shinbone, and heel. If the DXA is not available then only then this peripheral scan is used. And still the best choice for screening. The peripheral Test includes:

    • pDXA peripheral dual-energy X-ray absorptiometry: This measures the wrist and heel.
    • QUS (quantitative ultrasound): This uses sound waves to measure density, usually at the heel.
    • pQCT (peripheral quantitative computed tomography): This measures the wrist.

All the procedures performed for bone density scans are of non-invasive type.


What is the preparation required to perform the Bone Mineral Density Test?

All calcium supplements should be discontinued at least 24 hours before the test. If the person has had a procedure that involves ingesting a contrast medium for a barium study, CT scan, or MRI, you should wait at least a week because the contrast medium can interfere with the results. All metal belts and buttons must be removed prior to testing.


What is the main cause to perform the Bone Mineral Density Test?

Bone density tests are used to diagnose osteoporosis. This estimates the efficacy of bone loss and osteoporosis drugs and predicts future fracture risk. The recommendation for this test is higher for women over the age of 65. Men are advised to get tested after the age of 70. Young women and men of any age should have a bone density scan if they have risk factors, such as: 

    • Risk of fracture after age 50 Family history of osteoporosis 
    • Prostate cancer or breast cancer 
    • History of rheumatoid arthritis, 
    • thyroid disorder disorders and 
    • Anorexia nervosa
    • Early menopause 
    • Long-term use of corticosteroids or thyroid hormones 
    • Low body weight Significantly short stature 
    • Long-term use of tobacco or alcohol


What is the result of this test indicate?

Normal results: The test then yields two scores: the T-score and the Z-score.

The T-score compares bone density to that of another healthy young adult of the same sex who is being tested. 


T-score of -1 and above Indicate the normal bone density
T-score of -1 to -2.5 indicates low bone density and risk of osteopenia
T-score of -2.5 and above indicates low bone density and risk of osteoporosis


The Z-score compares bone mass to other people of the same age, sex, and size. A Z-score below -2.0 indicates low bone mass due to factors other than aging and requires further investigation. 

Abnormal results: An abnormal DEXA test does not help detect fractures. As with pre-existing risk factors, it only predicts the risk of future fractures. 

If the DEXA scan is abnormal this can also because of the following reasons such as :

    • Rheumatoid arthritis 
    • Inflammatory bowel disease 
    • Chronic kidney and 
    • Liver failure Respiratory disease 

When repeating the DEXA scan, it is recommended that the same site be tested. This helps in making accurate comparisons with the previous reports. While it is not always possible to test in a single location, it is necessary to compare density scores. 

X-rays cannot replace bone density tests, as they may not show osteoporosis until the disease is advanced. However, X-rays may be recommended along with a bone density scan to check for fractures in other parts of the body.


( Disclaimer: Information provided in this piece of article is purely for educational purposes only. All results must be clinically correlated with the patient’s data to make an accurate diagnosis.)


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