Osteoporosis
Osteoporosis, or thinning of the bones, is the reduction of the amount of calcium carbonate or phosphate deposited in the bone matrix. This may be simply the consequence of ageing, as a result of the cells which absorb bone being more active than those which deposit it. It may cause no symptoms until it results in a painful fracture as a result of weakening of the bones. Such fractures commonly affect the vertebrae, causing them to collapse (producing loss of height and the characteristic bent back known as the Dowager’s hump), the hip or the wrist. It is much more common in women after the menopause and it is more likely in those who are initially slight of build (because they have less bone in the bank to start with), who smoke cigarettes, who have taken little calcium and less exercise, and who abuse alcohol. In younger people it can occur after periods of immobility, such as may happen when a limb is immobilised in plaster after a fracture - because the continuous nature of the remodelling of our bones requires that they be stressed in order for new bone to be deposited: in the immobile bone and muscle mass disappear like snow on a hot stove. It is more likely in association with some other conditions such as an overactive thyroid, lack of testosterone in a male or in those with a strong family history. While it is possible to assess the density of bone using special X-ray techniques the value of screening is uncertain. The incidence may be reduced by ensuring adequate dietary intake of calcium, and reasonable amounts of exercise. In established cases bone loss maybe reduced by taking calcium supplements together with vitamin D, using hormone replacement therapy in women in whom there is no contraindication, or suppressing the activity of the cells - the osteoclasts - that absorb the bones. In severe cases infusion of the hormone calcitonin may help to reduce pain.
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