What is osteoporosis?
Osteoporosis - literally ‘porous bones’ - is a medical condition whereby your bones become fragile and are more likely to break. The common sites for breakage are the wrist, spine and hip. Although osteoporosis can be treated it is better to prevent it in the first place.
How does osteoporosis occur?
Two types of cells are constantly at work in your bones to allow your skeleton to grow and repair any damage such as fractures. ‘Osteoclasts’ break down the bone while ‘osteoblasts’ build it up again. Each ‘turnover’ cycle normally takes 200 days.
Many factors influence this process of bone replacement, including hormones, the amount of exercise you take and the amount of vitamin D and calcium in your diet.
The rate at which the bone replacement occurs is normally in balance. If more bone is lost than is replaced, your bones become less dense and you may develop osteoporosis. If you develop osteoporosis your bones can break more easily.
Who is at risk for osteoporosis?
All men and women are at risk for osteoporosis - everyone starts to lose some bone density from the age of 35 years and this is just a normal part of ageing. It is more common, however, in older women after the menopause, as they stop producing oestrogen, a hormone that protects the bones. After the menopause bone can be lost more rapidly over the next five to ten years.
Factors that increase the risk of osteoporotic fractures include:
- Personal history of a broken bone, especially a fragility fracture either occurring spontaneously, or as a result of low trauma such as a minor fall
- Family history of osteoporosis or low trauma fracture
- Early menopause
- Previous steroid therapy
- Anorexia nervosa
- Low body weight
- Poor diet
- Smoking
- Excessive alcohol intake
- Lack of exercise or mobility
- Prolonged untreated hyperthyroidism
- Prolonged over-treated hypothyroidism
- Other illnesses such as rheumatoid arthritis, coeliac disease, and primary hyperparathyroidism
What is the link between thyroid disease and osteoporosis?
Thyroid hormone affects the rate of bone replacement. Too much thyroid hormone (i.e. thyroxine) in your body speeds the rate at which bone is lost. If this happens too fast the osteoblasts may not be able to replace the bone loss quickly enough. If the thyroxine level in your body stays too high for a long period or the thyroid-stimulating hormone (TSH) level in your body stays too low for a long period then there is a higher risk of developing osteoporosis. There is also some evidence that people with low TSH levels may lose bone at a faster rate than those with normal TSH levels even when the blood thyroxine measurement is within the normal range, but this is still being studied.
Overactive thyroid (hyperthyroidism)
If you have hyperthyroidism, the first step is to treat the overactivity. Once the level of thyroid hormone in your body has been reduced to a normal level the rate of bone loss will no longer be so rapid and the bone strength may improve. Some people, however, will have persistent bone loss, with or without thyroid disease, and postmenopausal women are at particularly high risk of this. If you have had prolonged untreated hyperthyroidism and have other risk factors for osteoporosis and bone fractures, a bone mineral density scan two to three years after your thyroid treatment starts will help assess your risk. If a bone density scan shows osteoporosis then this can be treated with medication.
Underactive thyroid (hypothyroidism)
An underactive thyroid is not, in itself, a risk factor for osteoporosis, but if you are prescribed levothyroxine to increase your thyroid levels to the normal range you should have regular blood tests, at least once a year, to ensure your thyroid hormone levels are not too high.
How can I reduce my chance of osteoporosis?
You can help keep your bones healthy by eating a well-balanced diet containing calcium-rich foods, maintaining normal vitamin D levels, avoiding smoking, keeping your alcohol drinking to within recommended limits, and exercising regularly. High impact exercise, such as jogging or power walking, helps strengthen bones. Other exercises, such as pilates and yoga, may be useful in improving balance, therefore reducing the risk of falls which could break bones. Hormone Replacement Therapy (HRT) may help to reduce the risk of osteoporosis in women but it is now recommended only for the treatment of menopausal symptoms and may be associated with increased risk of other conditions depending on the individual. Spending 10-20 minutes every day in the sunshine provides the best source of vitamin D during summer months.
How much calcium should I take?
The National Osteoporosis Society recommends a daily intake of 700mg of calcium for men and women, including pregnant women, or up to 1,000mg daily if you are on osteoporosis drug treatments. If you are breast-feeding you need to increase your calcium intake by an extra 550mg daily.
What foods contain calcium and vitamin D?
Calcium is most easily obtained from (preferably low-fat) dairy products such as milk, cheese and yoghurt. One pint of skimmed milk contains 880mg of calcium. Certain types of fish, and green vegetables such as okra and watercress, are also a good source of calcium if you dislike or cannot consume dairy products. Oily fish, such as salmon, trout, mackerel, herring (including kippers) and fresh tuna contain vitamin D. Even if you are taking other medication for osteoporosis if there is not enough calcium or vitamin D in your diet and/or your bone density is reduced then you should talk to your doctor about taking calcium and vitamin D supplements.
Some important points....
- An overactive thyroid (hyperthyroidism) can increase the chance of getting osteoporosis
- Treatment of thyroid overactivity will reduce the rate of bone loss and bone strength mayimprove
- Talk to your doctor about a bone mineral density scan if you have had prolonged untreatedhyperthyroidism together with other risk factors for osteoporosis
- A diet rich in calcium and vitamin D, and regular high-impact exercise, can reduce yourchance of getting osteoporosis
- The National Osteoporosis Society recommends a daily calcium intake of 700mg for adult menand women, including pregnant women and an extra 550mg if you are breastfeeding
- People taking osteoporosis drug treatments might benefit from a daily calcium intake ofaround 1000mg a day
Further information can be obtained from: The National Osteoporosis Society (NOS)
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