Brittle bones - Causes of osteoporosis
NHS Choices Medical Reference
Osteoporosis is caused by bones losing their density.
Some people are more at risk than others.
How does osteoporosis develop?
Bones are at their thickest and strongest in early adult life and are constantly renewed and repaired through a process called bone turnover. However, as you age, this process is no longer balanced and bone loss increases. This means bone is very slowly broken down over time and your bones become less dense as you get older. This leads to the bone becoming weaker and more likely to fracture.
Who is at risk of osteoporosis?
Osteoporosis can affect men and women. It is more common in older people, but it can affect younger people too.
Women are at greater risk of developing osteoporosis than men. This is because changes in hormone levels can affect bone density. The female hormone oestrogen is essential for healthy bones. After the menopause, the level of oestrogen in the body falls, and this can lead to a rapid decrease in bone density. Women are at even greater risk of developing osteoporosis when:
- they have an early menopause (before the age of 45)
- they have a hysterectomy before the age of 45, particularly when the ovaries are also removed
- their periods are absent for a long time (more than six months) as a result of over-exercising or over-dieting
For most men who develop osteoporosis, the cause is unknown. However, there is a link to the male hormone testosterone, which helps to keep the bones healthy. Men continue to produce this hormone into old age, but the risk of osteoporosis is increased in men with low levels of testosterone.
In around half of men the exact cause of this is unknown, but known causes include:
Diseases of the hormone-producing glands
Many hormones in the body can affect the process of bone turnover. If you have a disease of the hormone-producing glands, you may be at higher risk of developing osteoporosis. Osteoporosis can be triggered by hormone-related diseases, including:
hyperthyroidism (overactive thyroid gland)
- disorders of the adrenal glands, such as Cushing's syndrome
- reduced amounts of sex hormones (oestrogen and testosterone)
- disorders of the pituitary gland
- hyperparathyroidism (overactivity of the parathyroid glands)
Other things thought to increase the risk of osteoporosis and broken bones include:
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