A Primer About Bone Density Test And T-Score

Risk Of Osteoporosis
Risk Of Osteoporosis

Osteoporosis is a condition when the bone becomes brittle due to loss in density. As a result of this, your bones become more susceptible to fractures. This condition is more common in women after menopause as well as in elderly people of both genders. But this can be prevented or slowed down to a certain extent with medications. For this, doctors first must do a bone density test for measuring the mineral content and density of bones. In this article, we will discuss in detail about bone density test and T-score; read on to know more about them.

Bone Density Test

A bone density test is done using X-rays or dual-energy X-ray absorptiometry (DXA or DEXA) of hip and spine bones. This can also be measured using a CT scan which uses computer software for measuring bone density. That said, the gold standard for osteoporosis and osteopenia diagnosis is DEXA.

The bone density test, also known as bone densitometry, helps the doctor to know whether there is a decrease in bone mass or not. This helps them to determine the risk for fracture. It typically measures the density of bones in the spine, hips, and lower arm. Moreover, this test helps to find decreasing bone density at an earlier stage so that osteoporosis treatment becomes useful.

Bone Density Test Results

The results of the bone density test are compared to two norms: T-score (healthy young adults) and Z-score (age-matched adults).


With the T-score, you can determine how much of your bone mass deviates from the bone mass of a healthy 30-year-old adult. In other words, it is a standard deviation from the average or mean; T-score osteoporosis is -2.5.

Listed below are the different values for T-score:

  • A T-score of 1 SD (+1 or -1) indicates normal bone density.
  • A T-score between 1 to 2.5 SD (-1 to -2.5), indicates low bone mass, i.e., osteopenia.
  • A T-score of 2.5 SD or below (less than -2.5) indicates osteoporosis.

Remember that as your bone density falls below the normal T-score, the risk for fracture increases.


The Z-score compares your bone density to the average bone density of people of your same age and gender. This is useful for diagnosing secondary osteoporosis, which can be present in pre-and post-menopausal women, men under the age of 50, young adults, and children. If the Z-score is 2 standard deviations below other individuals of the same age and gender, your doctor will consider other medications or medical conditions causing low bone density.

We hope that the details shared above clarified your doubts about the bone density test and T-score for osteoporosis.