Osteoporosis

Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to more porous bone, and consequent increase in fracture risk. Bones undergo continuous remodeling: osteoclasts resorb old bone, and osteoblasts synthesize new bone. With advancing age, the rate of resorption exceeds that of bone formation, causing bones to lose density and become more susceptible to fractures. The word "osteoporosis" is from the Greek terms for "porous bones". Osteoporosis is the most common reason for a broken bone among the elderly. Bones that commonly break include the vertebrae in the spine, the bones of the forearm, the wrist, and the hip. Until a broken bone occurs, there are typically no symptoms. Bones may weaken to such a degree that a break may occur with minor stress or spontaneously. After the broken bone heals, some people may have chronic pain and a decreased ability to carry out normal activities. Osteoporosis may be due to lower-than-normal maximum bone mass and greater-than-normal bone loss. Bone loss increases after menopause in women due to lower levels of estrogen, and after in older men due to lower levels of testosterone. Osteoporosis may also occur due to several diseases or treatments, including alcoholism, anorexia, hyperthyroidism, kidney disease, and after oophorectomy (surgical removal of the ovaries). Certain medications increase the rate of bone loss, including chemotherapy and glucocorticosteroids. Smoking and a sedentary lifestyle are also recognized as major risk factors. Osteoporosis is defined as a bone density of 2.5 standard deviations below that of a young adult. This is typically measured by a DXA (or DEXA) bone density scan. Prevention of osteoporosis includes a proper diet during childhood, hormone replacement therapy for menopausal women, and efforts to avoid medications that increase the rate of bone loss. Efforts to prevent broken bones...