Osteoporosis vs osteopenia: what the bone density terms mean

Osteopenia and osteoporosis are points on the same scale of bone density. The NHS describes osteopenia as the stage before osteoporosis, when a bone density scan shows lower bone density than the average for your age but not low enough to be classed as osteoporosis. Osteoporosis is the condition in which bones are weakened, making them fragile and more likely to break.

The important point is that osteopenia is not a disease in itself in the way osteoporosis is. The Royal Osteoporosis Society says it means your bones are weaker than normal but not as weak as in osteoporosis, that having lower bone density is just one risk factor for broken bones, and that it is normal for many people in later life. A diagnosis of osteopenia is a prompt to look after your bones and look at your overall risk, rather than an automatic call for treatment.

Bone density means how much bone tissue is inside your bones. The NHS says a bone density scan, called a DEXA scan, is a short painless procedure that takes 10 to 20 minutes depending on the part of the body scanned. Your bone density is compared with that of a healthy young adult, and the difference is expressed as a standard deviation, called a T score.

The Royal Osteoporosis Society says losing bone density is a normal part of ageing, which happens at different rates in different people. For some people lower bone density may be due to genetics, medication taken for another condition, or having naturally smaller, less dense bones. The NHS notes that women lose bone rapidly in the first few years after the menopause and that osteoporosis can also affect men, younger women and children.

The table uses the NHS and Royal Osteoporosis Society descriptions.

The NHS says that if your doctor suspects osteoporosis, they can work out your future risk of breaking a bone using an online tool such as FRAX or QFracture, and may refer you for a bone density scan. The decision on whether you need treatment depends on your risk of a future fracture, based on factors such as your age, sex and scan results.

The Royal Osteoporosis Society explains that a bone density scan can show you have less bone density than average but cannot measure how strong your bone tissue is. A doctor may therefore ask whether you have already broken a bone from a minor impact, whether you are taking medication known to affect bone strength and whether there is a family history of osteoporosis and broken bones. If you have a significant number of risk factors you may be referred for a fracture risk assessment, and medicine is considered only if that shows a high risk.

The NHS lists risk factors for osteoporosis, including high-dose steroid tablets for more than 3 months, certain medical conditions, a family history, particularly a hip fracture in a parent, some long-term medicines such as anti-oestrogen tablets after breast cancer, eating disorders, a low body mass index, not exercising regularly, and heavy drinking and smoking.

The Royal Osteoporosis Society lists a balanced, calcium-rich diet, safe exposure to sunlight so that skin makes vitamin D, regular impact and strength exercise, not smoking, keeping within recommended alcohol levels and lowering the risk of falling. The NHS adds a daily supplement containing 10 micrograms of vitamin D, and steps to reduce falls such as removing hazards at home and having regular sight and hearing tests.

If you have already been diagnosed with osteoporosis, the NHS says treatment is based on treating and preventing broken bones and taking medicine to strengthen bones. The Royal Osteoporosis Society and its helpline are listed by the NHS as sources of information and support.

Speak to a GP if you have broken a bone from a minor impact, have several risk factors for osteoporosis, are taking medicines that affect bone strength, or have been told you have osteopenia and want to understand your fracture risk. The Royal Osteoporosis Society says that if you have not been referred for further tests after a scan showing osteopenia, it is because your doctor thinks your risk of breaking a bone is low.