Bone Densitometry: Detecting Bone Loss

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As we get older we slowly start to see the visible signs of aging, like some laugh lines around the mouth or a few more gray hairs that just didn’t seem to be there yesterday. These outward changes will probably be noticed, but there is another change your body may be going through that is not as easy to detect. Approximately half of women and one-fourth of men over the age of 50 are at risk for developing osteoporosis, a disease that causes no symptoms but gradually makes bones weak and more likely to break. Fortunately, a painless medical test called bone densitometry can be used to help diagnose and treat the condition.

People Most Likely to Benefit from a Bone Densitometry Exam

·                     Women, especially those who are small-boned and Caucasian or Asian

·                     Older people

·                     Those with a previous pelvic fracture or a family history of the disease

·                     People with a lifetime diet that has been low in calcium

·                     Those who are inactive or smoke

·                     People who take certain medications, such as corticosteroids, some anti-seizure drugs, particular cancer drugs or too much thyroid hormone 

Bone densitometry, also called dual-energy X-ray absorptiometry or DEXA, typically uses low dose X-rays to measure bone density. It is a simple, non-invasive procedure that requires no anesthesia or special preparation before the exam. Patients can eat normally and take medications as directed, but calcium supplements should not be taken within a day of the test. There are two types of DEXA equipment: central DEXA devices measure bone density in the hips and lower back; peripheral DEXA machines measure bone density in the finger, hand, wrist, forearm, foot or heel. The procedure usually is done on an outpatient basis and can take between 10 to 30 minutes, depending on the bone being tested and the type of machine being used. Regular activities may be resumed immediately following the exam.

Test results from a bone densitometry exam include a T score and a Z score. The T score compares your bone density to the bone density of a young adult of the same gender with peak bone mass. A T score above -1 is regarded as normal. You may have the first stage of bone loss if your score is between -1 and -2.5. You will be diagnosed as having osteoporosis if your score is below -2.5. The T score is used to estimate your risk of developing a fracture. The Z score measures the amount of bone you have compared to your peers of the same age, gender and size. Additional testing may be necessary if the Z score is unusually high or low.

Bone densitometry is considered the most accurate way to diagnose osteoporosis and provide valuable information about fracture risk. The test can be repeated every few years to check bone density and determine if osteoporosis has remained the same or worsened.