Osteoporosis

Osteoporosis is a multifactorial disease. Although osteoporotic fractures occur most commonly in old age, risk factors can be traced back to childhood. A person's peak bone strength is established by the age of twenty. Although many people think of bone as an inert object, it is actually a living tissue, continually renewing itself to correct defects that occur from wear and tear. Cells called osteoclasts break down areas of bone and create cavities, which are then filled with new bone that is produced by the osteoblast cells. As we age, the rate of bone breakdown exceeds the rate of bone formation, and bone loss occurs at a rate of 1 percent each year. This increases to 2 to 5 percent per year during the first five years after menopause and also increases somewhat after the age of seventy-five. By the age of eighty, the average woman will have lost 30 percent of her skeleton. Thus, it can be understood that the larger the peak bone mass established in early life, the more will remain after years of progressive bone loss. A diet low in calcium and vitamin D and low physical activity in childhood decrease the peak bone mass and therefore increase the risk of osteoporosis. Premature menopause (natural or surgically induced) causes the rapid bone loss period associated with estrogen deficiency to occur earlier. Women, because of menopause, and because of a relatively lower peak bone density, are at higher risk that men. As bone loss occurs progressively through life, age itself is an important risk. Other risk factors include excessive alcohol use, caffeine consumption, race (white or Asian), a thin small frame, and a positive family history. Medical conditions such as hyperthyroidism and hyperparathyroidism, and drugs such as steroids and anticonvulsants, are also important contributors to osteoporosis.