Diagnosing Osteoporosis: How to Measure Bone Density

Osteoporosis is a bone disorder that develops when your bone mineral density and bone mass decreases. This can typically lead to a decrease in bone strength, making your bones more susceptible to fractures. It is the most common reason for a broken bone among the elderly.

Osteoporosis is considered a “silent” disorder because you typically don’t have symptoms, and you may not even know you have the disease until you break a bone. That said, properly diagnosing osteoporosis is essential.

How to Diagnose Osteoporosis

Diagnosing osteoporosis requires a test that can measure your bone mineral density (BMD). The most common (and preferred) test for measuring BMD is dual-energy x-ray absorptiometry (DEXA). 

A DEXA scan measures the BMD of your skeleton and is generally considered the most reliable way to diagnose osteoporosis and predict fracture risk. It uses low levels of X-rays to measure the density and mineral content of your bones. 

The DEXA scan results are provided as T-scores and Z-scores. The T-score measures the amount of bone you have in comparison to a normal population of younger people and is used to estimate your risk of developing a fracture. The Z score measures the amount of bone you have in comparison to those in your age group.

DEXA Scan Results: T-Scores

DEXA scan results are typically provided in the form of T-scores and Z-scores. T-scores reveal how high or low a person’s bone density is compared to healthy 25- to 35-year-old adults of your same sex and ethnicity. 

The standard deviation (SD) is the difference between your BMD and that of a healthy young adult. This result is your T-score. Positive T-scores indicate the bone is stronger than normal; negative T-scores indicate the bone is weaker than normal.

For instance, according to the World Health Organization, osteoporosis is defined based on the following bone density levels:

• A T-score within 1 SD (+1 or -1) of the young adult mean indicates normal bone density.
• A T-score of 1 to 2.5 SD below the young adult mean (-1 to -2.5 SD) indicates low bone mass.
• A T-score of 2.5 SD or more below the young adult mean (more than -2.5 SD) indicates the presence of osteoporosis.

The lower the scores, the lower the bone density, and the greater your risks for fractures.

DEXA Scan Results: Z-Scores

While T-scores compare bone density to a healthy adult of the same sex and ethnicity, Z-scores compare bone density to individuals of the same age, sex, and ethnicity. Z-scores are calculated in the same way, but the comparisons are made to someone of your age, sex, and ethnicity.

Because osteoporosis typically only affects older adults, Z-scores can be useful when looking at the bone density for children, teenagers, premenopausal females, and males under the age of 50 years.

Having a Z score that is lower than expected for your age may indicate that another condition is affecting your bone density levels, like secondary osteoporosis (osteoporosis caused by other medical conditions, medications, or lifestyle factors) or osteopenia (a condition where bone mineral density is lower than normal, but not as low as osteoporosis, and can increase the risk of fractures).

DEXA Scans for Diagnosing Osteoporosis

DEXA scans are considered the “gold standard” for measuring bone mineral density and are a great tool that healthcare providers can use for diagnosing osteoporosis. If the results of your DEXA scan indicate possible osteoporosis, it does not automatically mean that you will have a fracture. There are lifestyle changes and a number of available therapies that your doctor might prescribe to slow down bone loss and help prevent fractures.

Getting a DEXA scan is your first step for estimating future fracture risk. Checking for changes in your bone density is the best way to catch osteoporosis before it causes a bone fracture.

To schedule your next DEXA scan, visit NomadFitLab.com.