Bone Mineral Density Test and Osteoporosis
A bone mineral density test measures the density or quantity of minerals in your bones. The test is usually completed by using a CT scan or ultrasound. The test can be run on the hip, spine, wrist, finger, shin or heel bone(s). This information is critical in that through the bone mineral density test, the strength and overall health of your bones is able to be estimated. Now that we know what it measures and how it is done, let’s take a closer look at this test and the importance of bone mineral density in combating osteoporosis.
The results of any bone mineral density test will be compared to two “norms”; the “young normal” and the “age-matched normal” norms. The two norms work like this. Let’s say you are 45 years old. The first number, or the “young normal”; which your physician may also refer to as your T-score, is representative of the optimal or peak bone density of a 45 year old, same gender person. Additionally, this number helps in determining your chance or risk of bone fracture(s). As the number increases in regard to the T-score, so does your risk of bone fracture(s). The second norm, or the “age-matched number”, is also referred to as your Z-score. Your Z-score compares your bone mineral density to what is presumed or expected in someone your age and gender. The T-score seems to me more emphasized as the Z-score is somewhat variable and relative, and thus can be misleading.
Further, the difference between your bone mineral density (both scores/norms) and that of a healthy young adult (approximately age 25) is considered the standard deviation. The World Health Organization give the diagnosis category as follows: if your T-score is within one standard deviation of the “norm”, then you are considered to have normal bone mineral density; if your score falls below, specifically from -1 to -2.5 standard deviations, clearly indicates low bone mass and garners a diagnosis of osteopenia (the preclude to osteoporosis). Standard deviations lower than -2.5 indicate a diagnosis of osteoporosis, again according to the World Health Organization’s diagnosis categories.
This brings us to the question, who should be given a bone density mineral test?
- All woman aged 65 and older
- Younger postmenopausal women with one or more risk factors*
- Younger postmenopausal women who have a consistent or high incidence of bone fractures or breaks
* Risk factors include:
- Women who have had a total hysterectomy (ovaries removed)
- Women who are post menopausal and are not taking any type of hormone replacement therapy medication
- Individuals with vertebral abnormalities
- Individuals who are planning to receive or do receive, long-term steroid therapy
- Individuals with hyperparathyroidism
- Those individuals who are undergoing the testing of a new, approved osteoporosis medication therapy
It is worth noting that Medicare allows for individuals to not only have the bone mineral density test if they have any of these risks factors or simply qualify as listed above, but also to have it repeated every two years.
To summarize, let’s chart the World Health Organization information below, in regard to bone mineral density testing results:
- World Health Organization Definitions of Osteoporosis Based on Bone Density Levels
- Normal Bone Density is within 1 SD (+1 or -1) of the young adult mean.
- Low Bone Mass Bone density is 1 to 2.5 SD below the young adult mean (-1 to -2.5 SD).
- Osteoporosis Bone density is 2.5 SD or more below the young adult mean (> -2.5 SD).
- Severe (established) osteoporosis Bone density is more than 2.5 SD below the young adult mean and there have been one or more osteoporotic or bone fractures or breaks.
Source of chart: World Health Organization January 2008.
Osteoporosis Treatment: Find One The is Safe and Effective
