Fifty five percent of all Americans aged over 50 years have osteoporosis or thin spongy bone, that is highly susceptible to compression and breakage. One out of every two white women in US will fracture a bone in her lifetime. Although all long bones and vertebral bones are vulnerable, the most common fractures affect the hip bones. About 20% of post-menopausal women who fracture their hip bone die within a year of the fracture, while 20% of these women often have a second fracture one year down the road. The cost of treatment and nursing home rehabilitation of hip bone fracture patients runs into about one billion dollars a year. Currently about 10 million Americans have mild bone thinning or osteopenia. Another 34 million people have severe bone thinning or osteoporosis. This number is expected to increase in the years ahead with many more US citizens growing older.
Osteoporosis is mostly attributable to bone thinning usually after the age of 35 years, for various reasons. The normal rate of bone thinning due to age is 0-3% to 0,5% per year. Bone density usually peaks at the age 25 and remains there for another 10 years. Genes (family history), environment, sex, ethnicity, hormones, and medications influence bone density. Men tend to have heavier bones than women, even as African Americans tend to have heavier bones than Caucasians and Asian Americans. The short supply of sunshine in North America reduces the availability of Vitamin D, which normally helps the absorption of dietary calcium.
Women are particularly vulnerable to osteoporosis because of the progressive decrease in the level of estrogen needed to support bone density after the menopausal age of 45 years. Bone thinning is accelerated to 2% - 4% with up 25 % to 30% loss of bone density by age 55. The spongy nature of the bone is produced by normal formation of protein structure (collagen) of the bone without adequate calcification. Cigarette smoking, alcohol consumption, low protein and low calcium diets, as well as malabsorption from celiac sprue or biliary cirrhosis can all contribute to low bone density and easy bone fracture in older women.
Diseases like hyperthyroidism, anorexia nervosa or vigorous exercises (common among teenagers) can eventually cause amenorrhea (cessation of menses) with secondary bone thinning. Stroke and chronic arthritis, which cause immobility, also lead to loss of bone density. Abnormally high level of parathyrioid hormone, which normally maintains the normal level of blood calcium ends up stripping the bones of calcium, with marked reduction in density. High level of parathyroid hormone is often found in some forms of lung cancer as a paraneoplastic syndrome. Long-term use of heparin (blood thinner), phenythoin (anticonvulsant) and prednisolone (steroid) may also lead to loss of bone density.
Based on the what has been discussed so far it becomes necessary for every woman above 45 years to be aware of the high risk of bone fracture from osteoporosis and seek to be on a physician-prescribed preventive program. This includes X-ray and DEXA scan monitoring (T score of - 2.5 of or higher), adequate moderate outdoor exercises, and preventive medications like Alendronate (Fosamax) and estrogen replacement therapy (ERT).