How does menopause affect the bones?

We’re going to turn to the skeleton, because without the bone-strengthening effects of oestrogen, fractures become much more common in post-menopausal women. With Chris Smith to explain why, how we can monitor this and what we can do about it is Juliet Compston, Emeritus Professor of Bone Medicine at the University of Cambridge…

Chris - To what extent is a woman's bone fracture risk increased after menopause?

Juliet - It's hugely increased. So at the age of 50, one in two women can expect to have at least one fracture during their remaining lifetime.

Chris - That's a lot. So how does that compare with a man then?

Juliet - It's still quite common in men, but less so, so about one in five men.

Chris - And we think that this is down to the loss of oestrogen that occurs when a person goes through the menopause?

Juliet - It's partly due to that. Both in men and women, bone loss occurs around the age of 40 and continues throughout life. So it's not only due to oestrogen, it's due to many other factors. But in women during the menopause, there is an acceleration in the rate of bone loss, which is due to oestrogen deficiency. And that is one reason why the risk in women of having a fracture later in life is greater than in men.

Chris - How can you therefore spot who might be one of those one in two women?

Juliet - Well, we know there are a number of risk factors, which increase your risk of fracture. One is age, which obviously you can't do anything about apart from be aware that the risk of fracture becomes increasingly great as you age. If you've had a previous fracture, that is a very strong risk factor for having a subsequent fracture and should alert you and your GP to discuss being tested. And then there are other factors such as steroids, which you use in the treatment of many diseases, which increase your risk of fracture, things like rheumatoid arthritis, other diseases, which have an independent effect on fracture risk. If you have a family history, that is a strong strong risk factor, particularly if you have a parent who suffered a hip fracture. And then there are other risk factors like heavy smoking, alcohol abuse and body weight is very important. If you have a low BMI, you're at increased risk of fracture. Also, actually, if you're obese, you also have an increased risk of fracture.

Chris - What about exercise? Because we're often told that it's very hard to say how beneficial exercise is. That's loading your skeleton quite a lot, isn't it? Does that have a beneficial effect?

Juliet - Yes. Exercise is definitely good for the skeleton. We know that particularly in young people, exercise can actually increase the size of your bones as well as their mineral content and their strength. Whether exercise can reduce fractures in later life is slightly less certain. It can certainly increase your bone mass to some extent, but whether it's effective enough to reduce factor risk, hasn't yet been proven.

Chris - If someone presents to you with the sort of track record that you've just been outlining of risk factors, how do you investigate them?

Juliet - If they have one or more of the risk factors I've outlined, and particularly if let's say they're over the age of 50 whether a man or a woman, then I would first of all do something called FRAX, which is a free, factor risk algorithm on the Internet, which gives you a 10 year probability of fracture. And if that is very high then they probably are already indicated to have treatment. And if it's intermediate, you can do a test called a DEXA scan, which is a very simple test. It just involves lying on a couch for 10 to 15 minutes. There's no tunnel or anything. There's just a slim bar that goes over your body. That will actually give a measure of the amount of bone mineral in your spine and in your hip.

Chris - If it turns out someone's in the danger zone, having had these sorts of investigations, what can we do medically to try to reduce the risk of a person having a fracture?

Juliet - Well, we always start off by advising lifestyle measures, and they're the usual suspects. So stop smoking, don't drink too much alcohol, have a good balanced diet. Vitamin D - we believe it's important to have enough vitamin D through sunlight exposure where that's possible, and also physical activity as appropriate to the patient. But, in terms of pharmacological interventions, we have a really effective range of treatments which have been shown to reduce fracture risk. And these basically are divided into drugs which stop bone being removed excessively from the skeleton. And the most well-known of these are the bisphosphonates, but hormone replacement therapy, HRT, which of course contains oestrogen also acts in the same way. And then we also have a newer group of bone-forming agents, which actually stimulate bone formation, which can also be used.

Chris - And are these any good?

Juliet - They are very good. They reduce fractures in the spine, the hip and elsewhere in the body