What is osteoporosis?

Osteoporosis is a condition in which there is a thinning of the bones, causing them to fracture (break) more easily. It is most commonly associated with older people. While all people experience some thinning of the bones (loss of mass) as they get older, osteoporosis refers to the stage when the bone mass reaches a level at which fracture is likely to occur.

The most commonly associated characteristic of osteoporosis is probably fragility fractures. This is when the bones break even if there is little or no trauma to them. Fragility fractures occur most often in the wrist, hip and spine.

Osteoporosis can occur in men and it can occur at any age from childhood onwards, however both of these cases are rare. It is more commonly associated with post-menopausal women.

What is going on in the bones?

Bone is a living tissue which needs to be constantly renewed. Otherwise it would lose its strength.

Old bone is constantly being broken down and replaced by new, stronger bone. This process is called bone remodelling.

There are two main types of cell in the bone: osteoclasts which destroy bone and osteoblasts which make new bone. These are both formed in the bone marrow.

As a person gets older, the osteoclasts become more active, while the osteoblasts become less active. This basically means more bone is removed and less bone is formed, resulting in a thinning of the bones.

During childhood and adolescence the bones grow and become more solid. By the mid-20s, the amount of bone in the skeleton has reached its maximum. This is known as the peak bone mass and it is important in determining whether a person is at risk from developing osteoporosis later in life. The more peak bone mass a person has at this age, the less chance they have of developing osteoporosis later in life.

There are a number of factors which help determine peak bone mass, although not all of them are fully understood. They include:

  • Calcium intake
  • Genetic (hereditary) predisposition
  • Physical exercise
  • Sex hormones

The amount of bone in the skeleton starts to decrease around the age of 40 and continues to decrease throughout life.

What are the main risk factors?

Both men and women of almost all ages can get osteoporosis. However it is usually found in older women. The main risk factors are:

  • Being female
  • Being 40 or older
  • Being postmenopausal
  • Having a premature menopause
  • Having a sedentary lifestyle (little or no routine exercise)
  • Having a diet that is low in calcium
  • Being thin
  • Amenorrhoea (the absence of menstrual periods. This is common in women with anorexia nervosa)
  • Thyroid disease (over-production of the hormone thyroxine, which is made by the thyroid gland, causes bone loss and may therefore result in osteoporosis)
  • Some forms of cancer are associated with the rapid destruction of bone
  • Smoking
  • Drinking alcohol to excess
  • If osteoporosis runs in your family
  • Having a history of one or more fragility fractures
  • Ethnic background (for example, Caucasians are more at risk from osteoporosis than African-Americans)

What are the symptoms of osteoporosis?

Most people have no symptoms until a fracture occurs. The most common of these are:

Wrist fractures

These are also known as Colles’ fractures after the Irish surgeon who first described them. They usually occur when the person falls forward from an upright position, putting their hand out to help break the fall. They most commonly occur in women aged 50-70 years.

Spine (vertebral) fractures

With regard to osteoporosis, the term ‘spine fracture’ can be misleading because it doesn’t actually refer to the breaking of a bone. Instead it describes a change in the shape of the vertebrae (the bones that make up the spine). The vertebrae are like bricks, located one on top of the other. In osteoporosis, these vertebrae can become crushed or compressed. This can occur in the back, middle and/or front of the vertebrae. These spine fractures can occur as the result of a fall, however most of the time they occur spontaneously as the result of a simple activity, such as coughing or turning.

Some people experience little or no pain when a spine fracture occurs. Others have severe pain. If a few vertebrae are affected, there may be an obvious loss of height. Height loss is often accompanied by curvature of the spine. This leads to a rounding of the back and is known as ‘dowager’s hump’. This change in the shape of the back causes the chest and the abdomen to be pushed downwards, often resulting in pain and discomfort. Because of the change in body shape and the possibility of pain and discomfort, depression is common amongst people affected by spinal osteoporosis.

Hip fractures

These are fractures which occur at the top part of the femur (thighbone). Almost all hip fractures occur when the person has a fall of some sort. Hip fractures are usually associated with much older people. (The average age of people who have hip fractures is around 80 years.) The consequences of a hip fracture can be devastating. It is estimated that around 15-20% of people who have a hip fracture die within six months. Of those who survive, around 75% never regain the same level of independence as t hey had before the accident.

What can I do to reduce my chances of developing osteoporosis?

  • Ensure you are getting enough calcium in your diet. Calcium helps to achieve a good peak bone mass and reduces age-related bone loss later on in life. The best source of calcium is in dairy products, such as milk and cheese. For those who have an intolerance to dairy products, calcium supplements can be taken. If you cannot tolerate, or simply dislike dairy products, consult your doctor about which supplements are best, as most health shops and chemists have a bewilderingly large number of supplements, so it can be difficult to know which ones are best.
  • Ensure that the rest of your diet is balanced. A balanced diet is very important for the bones.
  • Avoid excessive dieting. This can have a very harmful effect on the bones. People with anorexia nervosa can get severe osteoporosis, even if they are still young. Anorexia often develops during adolescence when the skeleton should be growing. This leads to a low peak bone mass, which can in turn lead to osteoporosis at an earlier age.
  • Take routine exercise, as this is good for the bones. In older people, exercise can slow down bone loss, as well as improving agility making it less likely that a fall will occur. Avoid over-exercising, as this can be harmful to the bones, especially in young women.
  • Do not smoke. If you already do, try to give up. Smoking is bad for your bones. There is also evidence to suggest that smoking actually reduces the effectiveness of some treatments for osteoporosis.
  • Moderate alcohol intake may actually be beneficial. However excessive alcohol intake may be harmful to the bones.
  • Be vigilant. If you are an older person, try to avoid situations where a fall may occur, for example, if the ground is icy. Also watch carefully for uneven steps or cracks in the ground which may result in an accident.

How is osteoporosis diagnosed?

If you suspect you have osteoporosis, or if you feel you may have a chance of developing it, for example if it runs in your family, visit your doctor immediately.

Your doctor will take a detailed medical and family history, which will help to determine your risk of developing osteoporosis. Established osteoporosis may be visible on routine X-rays, but this is not always the case.

If osteoporosis or slight bone thinning is suspected, a particular type of bone scan – a DEXA scan – can be carried out to measure the density of the bones. This is a simple, painless procedure that uses very low doses of radiation. It is currently the most accurate and reliable means of assessing the strength of your bones and your risk of breaking a bone.

How is osteoporosis treated?

There are a number of effective treatments for osteoporosis, all of which are aimed at reducing fracture risk by replacing or strengthening bone. Which treatment you are prescribed by your doctor will depend on a number of factors – including age, sex and medical history.

Calcium and vitamin D can help to prevent osteoporosis, and supplements are recommended for all postmenopausal women if dietary intake is inadequate.

Bisphosophonates, which work by reducing the breakdown of bone (bone resorption), are currently the most widely prescribed anti-osteoporotic treatment. They can cause stomach upset in some people, but are effective and treatment has been shown to be safe in the long-term.

SERMs (selective estrogen receptor modulators) also act to prevent bone resorption. They are used mainly in postmenopausal women as a preventive measure, or for the treatment of those with predominantly spinal osteoporosis.

Parathyroid hormone works by increasing bone formation and is used in patients with severe osteoporosis and multiple fractures. It is normally given for a limited time period and followed by treatment with an antiresorptive agent – such as a bisphosphonate. Strontium ranelate is another treatment that works by increasing bone formation, while at the same time reduces breakdown of bone.

Hormone Replacement Therapy (HRT) is no longer primarily indicated for the treatment of osteoporosis, due to concerns about its long-term usage and the availability of safer and effective alternatives. However, for patients who are on HRT for other symptoms, its effect on bone in reducing risk of fractures is useful.

Visit the irishhealth.com Osteoporosis Clinic for more information on osteoporosis

Last Reviewed: 1st December 2006

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