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How Bone Density Test Is Done - Interpreting Bone Density Scores

Updated on August 15, 2011

A bone mineral density (BMD) scan or bone densitometry is a screening test, which works by emitting low dose x-ray radiation to measure bone loss or the amount of calcium in the bones (bone calcium density). With the help of bone densitometry test, the orthopedic doctors can determine the presence of osteoporosis or risk of fractures due to aging and longevity. It is considered the best method to diagnose osteoporosis and is used especially for the hips and lower back. The test is painless and noninvasive and there is no risk of radiation exposure. Also, it must be noted that dual energy x-ray absorptiometry (a form of densitometry) is another means of measuring bone density used by ortho doctors, especially to detect osteoporosis. Osteoporosis is a disease that weakens bones with the gradual loss of calcium. This calcium loss causes the bones to become more fragile and to break easily in a fall. Most old women after menopause are affected by osteoporosis. Still, osteoporosis may also affect old men. Once medical treatment has been established, the bone density test continues to be effective when monitoring and diagnosing other bone related disorders.

Precautions To Be Taken Before Undergoing Bone Density Test:

  • Before coming to have a bone density test performed, it is really necessary to stop eating any food and avoid taking any calcium supplements 24 hours before the exam.
  • It is also recommended that the patient must wear light clothing without wearing any metal accessories such as watches, jewelry, or metal belts. Even if a patient comes wearing these items, the examiner removes these before the procedure is initiated.
  • Also, it must be noted that if a person has recently undergone a test requiring injection of contrast material in the body, it is important to wait for 10 to 14 days before densitometry to get the optimal results.
  • Again, it must be understood that pregnant women should not undergo this exam as it involves exposure to x-ray radiation.
  • Breast-feeding mothers must inform the doctor about their status before the examination.

How Bone Density Test Is Performed?
How Bone Density Test Is Performed?

How Bone Density Test Is Done?

At the time of examination, a person is asked to undress and put on a gown. Once done, the patient is put in a supine position on radiography table. Legs are positioned on a padded box, so that the pelvis and lower back are flat on the table, to observe the hip and other areas to measure bone loss. The foot of the person is put in a brace that allows inward rotation of the hip. While the person is still, from underneath the table radiation is emitted which passes through the area to study. On top of the patient lies a detector, which moves along the body to click x-ray images. The detector measures the bone density and generates images, which appear on the computer for the evaluation by the radiation technologist. The test takes between 10 to 30 minutes and does not cause any pain to the patient.

Watch Live Bone Density Scan

Interpreting Bone Density T Score
Interpreting Bone Density T Score
Interpreting Bone Density Z Score
Interpreting Bone Density Z Score

Interpreting Bone Density Scores

After the radiation technologist interprets the data from the bone mineral density test, he/she sends a report to the ortho doctor so that he can communicate the results to the patient. These results come with two parts and can be interpreted as:

  1. T score, which shows the patient's bone mass, compared with that of an adult of the same sex to total bone mass. If the score is above -1 is considered as normal and if between -1 and -2.5 is considered to be in the first stage of bone loss meaning osteopenia and if it is less than -2.5 is considered osteoporosis. T score measures the risk of fractures.
  2. Z score also shows the patient's bone mass but compared with other normal people of same size, sex, and age.

Finally, the orthopedic specialist informs the person if he/she needs to undergo further tests and what is the treatment he/she should follow.

HubMob Weekly Topic: The return of the Health Hubs - Hub #5 by soni2006
HubMob Weekly Topic: The return of the Health Hubs - Hub #5 by soni2006


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    • D.Virtual.Doctor profile image

      Funom Theophilus Makama 7 years ago from Europe


      Tells a patient if she has osteoporosis

      Helpful predicting risk of broken bones

      Determine the need for treatment and monitor its effectiveness


      Risk of fracture is dependent on more factors than just bone density

      May encourage patients to take unnecessary medications

      Exposes patient to low levels of radiation

      Current Recommendations - The U.S. Preventative Services Task Force recommends a bone density test at least once for all women age 65 and older.

      Who should have a bone density test?*

      all postmenopausal women under age 65 who have one or more additional risk factors for osteoporosis (in addition to being postmenopausal and female)

      all women age 65 and older regardless of additional risk factors

      postmenopausal women who sustain a fracture

      women who are considering therapy for osteoporosis if bone density testing would facilitate the decision

      women who have been on hormone replacement therapy (HRT/ERT) for prolonged periods

      This is such an awesome hub. Very contemporary and indeed breath- taking. I am so privileged to read this hub because I am duly informed and educated. Hoping to read more of such hubs from you. Cheers!


    • soni2006 profile image

      Rajinder Soni 7 years ago from New Delhi, India

      Lamme, you have always been a great support for my hubs and you have always praised about my knowledge. I salute you for your generosity, kindness, and wisdom.

    • Lamme profile image

      Lamme 7 years ago

      soni2006, great hub! I really had no idea how the test was performed, but I often hear about it. Thanks for such a well researched and useful article. Can I add something to your conversation with beebong? Women also need to be sure that they are getting adequate vitamin D. Research has shown that the majority of people have a vitamin D deficiency and vitamin D plays a crucial role in helping the body absorb calcium. Thanks again, you've provided a wealth of information as always!

    • soni2006 profile image

      Rajinder Soni 7 years ago from New Delhi, India

      I think you are right beebong, but I need to modify your comment. Women should keep on drinking plenty of milk and eating calcium rich diet from their childhood and all their life, so that they get lots of calcium in natural form.

    • beebong profile image

      beebong 7 years ago from UK

      It might help to prevent that illness by telling young woment to drink plenty of milk during there teens. Apparently that prevents problems with bone wastage later in life....hope this helps.