Osteoporosis is a disease in which bones become fragile and are, therefore, more likely to break (NOF, 2004). Thus, the common perception that bones are inert structures, like wooden beams, is incorrect. For, a bone is actually a living tissue, which is constantly being remodeled. After age 35, however, on the average a little more bone is lost each year than is gained during this remodeling. Between 40 and 50, men characteristically lose 0.5 to 0.75% of bone mass yearly, while women lose it at more than twice that rate. Bones that were once sturdy may become lighter and fragile, with their interiors resembling lacy honeycombs. The rate of natural loss increases substantially after age 50. If its severe enough, the thinned-out bones become porous, and osteoporosis develops, which literally means bone porosity (Walford, 2000, p. 131). Consequences and Implications: Osteoporosis is often called the "silent disease" because bone loss occurs without any symptoms. Therefore, people may not know they have osteoporosis until their bones become so weak that a sudden strain, bump or fall causes a fracture or a vertebra to collapse. If a vertebra or vertebrae collapse, it then results in severe back pain, loss of height or even spinal deformities such as kyphosis or stooped posture. Typically, osteoporosis results in hip, spine, wrist, and rib fractures, although any bone can be affected (NOF, 2004). Although any fracture is painful and slow to heal, it is important to note that fractures caused by osteoporosis can be particularly debilitating since older people are more prone to the disease, which implies further slowness of recovery and other age-related problems. For instance, an average of 24% of hip fracture patients, aged 50 and over, die in the year following their fracture. In addition, an osteoporosis patient can fracture a bone very easily even through small incidents such as slipping on a rug, lifting a bag of groceries, or a friendly hug (Walford,...

132).
Causal Factors: As already observed, one major cause of osteoporosis is the natural ageing process. But the actual onset and progression of the disease is complex. Usually, a biologically active form of vitamin D regulates absorption of calcium from the gut. With age, a deficiency develops in the body's ability to convert regular vitamin D to this active form. This leads to decreased absorption of calcium and thereby, lowered blood calcium. The small drop in blood calcium further triggers an increased release of a hormone from the parathyroid glands, which are located on either side of the neck. This parathyroid hormone (PTH) raises the blood calcium by drawing calcium from the bones since blood calcium has to be maintained at normal levels for the rest of the body's mechanisms to function. The kidneys then remove excess PTH (Walford, 2000, p. 132).

One reason why osteoporosis develops late in life is because the blood level of PTH may increase secondary to a decline in kidney function, which normally occurs with age. The situation is exacerbated in menopausal women since the amount of estrogen in the blood is also decreased, and estrogen makes bone less sensitive to dissolution by PTH. Another hormone, calcitonin, secreted by the thyroid gland, serves to inhibit bone resorption. However, again, the level of this hormone decreases with age. Thus, all these factors contribute to the development of bone porosity or osteoporosis (Walford, 2000, p. 132).

However, while osteoporosis may be attributed largely to the ageing process, it is important to note that certain people are more likely to develop osteoporosis than others. Thus, it is well-established that there are certain "risk factors," which may increase an individual's likelihood of developing osteoporosis. These risk factors are: personal history of fracture after age 50; current low bone mass; being female; family history; being…