What is a Bone Mineral Density Test?
A bone mineral density test is an easy reliable test that measures the density, or thickness, of your bones. It measures the amount of mineral (calcium) in a specific area of bone. The more mineral you have in the bone measured, the greater your bone density or bone mass.
A BMD test can:
- Measure the density of your bones
- Detect osteoporosis before a fracture occurs
- Help to predict your chances of fracturing in the future
- Monitor the effectiveness of treatments for osteoporosis
What is it like to have a BMD test and is it safe?
The most standardized method to measure bone density is called dual x-ray absorptiometry (DXA) of the hip and spine. It is a quick and easy test. It is not necessary to undress as long as you have no buttons, zippers, or snaps on your clothing from your chest to thigh.
You simply lie on a table while a fast, painless low-dose x-ray is taken. Nothing is injected or swallowed. The radiation is so low that no protective shields are necessary for the patient or the x-ray technologist. In fact, the radiation approximates the background radiation you receive flying in an airplane from New York to California. That is only 10% of the radiation exposure of a chest x-ray.
There are two scores used by experts to interpret bone density test results, the T-score and the Z-score.
What is a T-score and what does it mean?
The World Health Organization (WHO) uses T-scores to define normal bone mass, low bone mass (or osteopenia), and osteoporosis. The T-score compares your bone density to the average bone density of young healthy adults of your same gender . Normal Bone mass is -1.0 and above, Low Bone Mass is -1.0 to -2.5, Osteoporosis is -2.5 and lower.
What is a Z-score and what does it mean?
A Z-score compares your bone density to the average values for a person of your same age and gender. A low Z-score (below -2.0) is a warning sign that you have less bone mass (and/or may be losing bone more rapidly) than expected for someone your age. If your Z-score is low, your medical professional may recommend additional tests to better understand why your bone mass is so low or she/he may refer you to an osteoporosis specialist.
What is low bone mass and how is it diagnosed?
Low bone mass, often called osteopenia, is not a disease but a condition in which your bone density, or bone thickness, is lower than the average bone density of young healthy adults of your same gender. Low bone mass is diagnosed when your T-score is between -1 and -2.5. If you have been diagnosed with low bone mass, it is important to speak to your doctor or medical professional about your results and take action to promote healthy bones.
What is osteoporosis and how is it diagnosed?
Osteoporosis is a disease that causes bones to become thin and weak, often resulting in fractures (broken bones) A BMD test can diagnose osteoporosis when your T-score is -2.5 or below. The lower your bone mass, the greater your risk for fracture. Osteoporosis can also be diagnosed if you have a history of fractures without trauma.
What if I have low bone mass or osteoporosis?
If your BMD test results indicate that you have osteoporosis, your doctor or medical professional may prescribe a medication for osteoporosis treatment. If you have low bone mass along with strong risk factors for osteoporosis and/or fracture, your doctor may decide to prescribe a medication for osteoporosis prevention. After a medication is prescribed for you, repeat BMD tests may be used to monitor how your bones have responded to the treatment.
From : www.nysopep.org