As our bones grow, they increase in density until it reaches a maximum in our late 20s. However, as we get older, it then starts to decrease once more, especially for women after the menopause due to a reduction in oestrogen levels. Various medical conditions can also cause us to lose bone density, and certain medications can speed it up, but for both men and women it decreases as we move into older age.
The T-score results from a special type of X-ray called a Dual Energy X-ray Absorptiometry (DEXA for short) which examines a person’s bone density to discover how much has been lost. This is a non-invasive procedure which sees you lying on a firm hospital couch and having x-rays passed over the relevant parts of your body. The machine will measure the X-rays that your bones absorb, and the result is your T-score.
What A Bone Density Test Can Do
The bone density test can check whether your bone density is decreasing, by measuring how much radiation passes through your bones and then analysing this on a computer. Your results will be compared to the standards for someone of your age, gender and ethnicity, or the bone density of a young, healthy adult. This result can then help to advise the clinician whether you need to embark on treatment and what that should be.
Guide To Understanding T Scores
|T-score||Bone Mineral Density (BMD)||Fracture Risk|
|+1 to -1||Healthy||Minimal|
|-1 to -2.5||Osteopenia||Moderate|
|-2.5 to -3.0||Osteoporosis||Elevated|
|-3.0 and lower||Severe osteoporosis||Maximum|
The T-score is an accurate way to determine whether you are at an increased risk of osteoporosis before you ever break a bone, which means that preventative measures can be begun in good time or osteoporosis caught in its early stages. Such measures can include lifestyle changes, such as:
- Eating a balanced diet, rich in calcium
- Spending more time in the sun to increase levels of vitamin D
- Doing regular weight-bearing exercise like walking or running
If your T-score is -1 or above then your bone density is considered normal and you’re at no greater risk than anyone else in that range of breaking a bone. The risk increases for anyone in the -1 to -2.5 range as that is when osteopenia, a loss of bone density midway between healthy and osteoporosis, is evident. Osteoporosis will be diagnosed for anyone with a T-score below -2.5 and that becomes more severe as the score gets lower.
When to seek treatment
According to the NHS website, a bone density scan will usually be advised if you’re:
- Over 50 and at risk of developing osteoporosis
- Under 50 with other risk factors, such as smoking or a previous broken bone
The denser your bones are, the less likely they are to break, but you won’t have symptoms of osteoporosis until you actually suffer a break. An investigation can then begin to discover if your bones are less dense than normal and at greater risk from further breaks due to osteoporosis. The DEXA X-ray, therefore, is a useful test to determine if someone is at risk of osteoporosis before they ever break a bone, meaning that it can be caught in its early stages and any necessary treatment begun. This is consequently a valuable tool in the prevention of osteoporosis through timely lifestyle changes, such as increased calcium intake and weight-bearing exercise, where possible.
Page reviewed by Carole Kerton-Church, Regional Clinical Lead on November 23, 2021