Osteoporosis

FDr Trisha Macnair
ew women are aware that they have brittle bones, or osteoporosis, until the damage is done. But the key to prevention is as simple as a healthy and active life.

What is it ?
Osteoporosis means just as the name suggests - porous bones (also often called thinning of the bones). It's remarkably common: one in three women and one in 12 men in the UK develop osteoporosis, a rate that's increasing by about ten per cent a year. Yet despite this, few people are aware of it or the damage it can lead to.

This may be because we tend to think of our bones as solid, static objects. But, in fact, our bones are an active, dynamic organ and - just like the rest of the body's organs - they're involved in a constant process of cell growth, repair and change. And this process can go wrong.

Our bones
Rather than being solid objects, our bones are made from a honeycomb of strands formed by the protein collagen and hardened by calcium salts and other minerals. This honeycomb is filled with bone marrow and blood vessels and protected by a dense outer shell. Scattered throughout are millions of living bone cells, which continually break down and replace old bone. Our bones are completely renewed over a period of about ten years.

While we're young, our bones continue to grow and get denser and stronger. They reach maximum strength at 25 to 30 years, known as peak bone mass. After this, sadly, it's all downhill. Bone is lost faster than it can be replaced and the holes of the honeycomb become larger, leaving bones weaker and more likely to break. (Compare pictures of healthy bone with osteoporotic bones at the website of the National Osteoporosis Society.)

Women are especially prone to the disease, owing to loss of oestrogen after the menopause
Unless you take special precautions, osteoporosis can develop, especially if you're particularly vulnerable. Women are especially prone to the disease, owing to loss of oestrogen after the menopause.

In osteoporosis, fractures can occur anywhere in the skeleton, but especially in the wrist, spine and hip.

Risk factors
The risk factors for osteoporosis include:

1. Getting older, although in some cases it can also affect children and adolescents.
2. Loss of oestrogen as a result of the menopause (especially early menopause), hysterectomy (especially if the ovaries are removed), infrequent periods (especially linked to anorexia or excessive exercise).
3. Long-term use of high-dose steroids.
4. Family history (ie, a genetic tendency).
5. Lack of exercise.
6. Smoking.
7. Excessive alcohol consumption.
8. Low testosterone levels in men.

Diagnosis
Many people don't discover they have osteoporosis until they break a bone as the result of a relatively minor fall. Screening tests - usually involving a bone density scan - do exist, although you may have to pay for them privately.

Prevention
The most important thing you can do to prevent osteoporosis developing is to keep your bones strong and healthy while you're young. The aim is to maximise peak bone mass, reached at the end of your 20s. If this is high, you'll have greater bone reserves to help you face the natural loss of ageing. If you're already in your 30s, the priority is to maintain bone strength.

This can be achieved through:

1. A calcium-rich diet.
2. Exercise, especially weight-bearing. Tennis players, for example, have a 30 per cent higher bone density in their serving arm than in their non-serving arm. Try running, cycling or bouncing on a trampoline for at least 30 minutes three times a week. Simply jumping up and down 50 times a day will keep your bones strong.

Treatments
Once you've lost bone mass, it can't be regained. However, you can prevent further damage by:

1. strengthening the remaining bone structure
2. preventing further thinning

Treatments include:

1. Hormone replacement therapy (HRT) - the hormone oestrogen significantly reduces the risk of osteoporosis. However, research has shown that long-term use of HRT may be associated with significant risks as well as benefits, in particular doubling the risk of breast cancer and increasing the risk of heart disease and stroke. Therefore, each individual woman needs to weigh up the risks and benefits before deciding whether to use it.
2. Bisphosphonates - these drugs, such as alendronate and etidronate, switch off the cells that break down bone, so bone building can take over.
3. Calcium and vitamin D supplements - these are especially useful for those on a limited diet or who are housebound.
4. Calcitonin - a hormone made by the thyroid gland that inhibits the cells which break down bone.
5. Testosterone supplements for men.
6. Selective estrogen receptor modulators (SERMs) - these are a new type of drug that acts like a synthetic form of hormone replacement. They reduce the risk of osteoporosis and heart disease, but don't increase the risk of breast or endometrial cancer.