Brittle bones - Diagnosing osteoporosis

Osteoporosis is often diagnosed after weakened bones have led to a fracture.

If you're at risk of developing osteoporosis, your GP may refer you for a bone mineral density scan, known as a dual energy X-ray absorptiometry (DEXA, or DXA) scan.

Normal X-rays are a useful way of identifying fractures, but they aren't a reliable method of measuring bone density.

DEXA (DXA) scan

A DEXA scan can be used to help diagnose osteoporosis. It's a quick, safe and painless procedure that usually takes about five minutes, depending on the part of the body being scanned.

The scan measures your bone mineral density and compares it to the bone mineral density of a healthy young adult and someone who's the same age and sex as you.

The difference between the density of your bones and that of a healthy young adult is calculated as a standard deviation (SD) and is called a T score.

Standard deviation is a measure of variability based on an average or expected value. A T score of:

• above -1 SD is normal
• between -1 and -2.5 SD is defined as decreased bone mineral density compared with peak bone mass
• below -2.5 is defined as osteoporosis

Although a bone density scan can help diagnose osteoporosis, your bone mineral density result isn't the only factor that determines your risk of fracturing a bone.

Your age, sex and any previous injuries will need to be taken into consideration before deciding whether you need treatment for osteoporosis.

Your doctor can help you take positive steps to improve your bone health. If you need treatment, they can also suggest the safest and most effective treatment plan for you.