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. Bone-density loss accelerates beginning about two years before menopause, and Dr. Jocelyn Wittstein says women could lose about 10% of their bone density during that relatively narrow period. 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 in those with osteoporosis include a good diet, exercise, and fall prevention. Lifestyle changes such as stopping smoking and not drinking alcohol may help. Bisphosphonate medications are useful to decrease future broken bones in those with previous broken bones due to osteoporosis. In those with osteoporosis but no previous broken bones, they have been shown to be less effective. They do not appear to affect the risk of death.
Osteoporosis becomes more common with age. About 15% of Caucasians in their 50s and 70% of those over 80 are affected. It is more common in women than men. In the developed world, depending on the method of diagnosis, 2% to 8% of males and 9% to 38% of females are affected. Rates of disease in the developing world are unclear. White and Asian people are at greater risk for low bone mineral density due to their lower serum vitamin D levels and less vitamin D synthesis at certain latitudes.
Signs and symptoms
Osteoporosis has no symptoms, and the person usually does not know they have osteoporosis until a bone is broken. Osteoporotic fractures occur in situations where healthy people would not normally break a bone; they are therefore regarded as fragility fractures. Typical fragility fractures occur in the vertebral column, rib, hip, and wrist. Examples of situations where people would not normally break a bone include a fall from standing height, normal day-to-day activities such as lifting, bending, or coughing.
Fractures Fractures are a common complication of osteoporosis and can result in disability. Acute and chronic pain in the elderly is often attributed to fractures from osteoporosis and can lead to further disability and early mortality. These fractures may also be asymptomatic. The most common osteoporotic fractures are of the wrist, spine, shoulder, and hip. The symptoms of a vertebral collapse ("compression fracture") are sudden back pain, often with radicular pain (shooting pain due to nerve root compression) and rarely with spinal cord compression or cauda equina syndrome. Multiple vertebral fractures lead to a stooped posture, loss of height, and chronic pain with resultant reduction in mobility.
Fractures of the long bones acutely impair mobility and may require surgery. Hip fracture, in particular, usually requires prompt surgery, as serious risks are associated with it, such as deep vein thrombosis and pulmonary embolism. There is also an increased risk of mortality associated with osteoporosis-related hip fracture, with the mean average mortality rate within one year for Europe being 23.3%, for Asia 17.9%, United States 21% and Australia 24.9%.
Fracture risk calculators assess the risk of fracture based upon several criteria, including bone mineral density, age, smoking, alcohol usage, weight, and gender. Recognized calculators include FRAX, the Garvan FRC calculator and QFracture, as well as the open-access FREM tool. The FRAX tool can also be applied in a modification adapted to routinely collected health data.
The term "established osteoporosis" is used when a broken bone due to osteoporosis has occurred. Osteoporosis is a part of frailty syndrome.
Risk of falls
There is an increased risk of falls associated with aging. These falls can lead to skeletal damage at the wrist, spine, hip, knee, foot, and ankle. Part of the fall risk is because of impaired eyesight (e.g. glaucoma, macular degeneration), balance disorder, movement disorders (e.g. Parkinson's disease), dementia, sarcopenia (age-related loss of skeletal muscle), and collapse (transient loss of postural tone with or without loss of consciousness). Causes of syncope are manifold, but may include cardiac arrhythmias (irregular heart beat), vasovagal syncope, orthostatic hypotension (abnormal drop in blood pressure on standing up), and seizures. Removal of obstacles and loose carpets in the living environment may substantially reduce the number of falls. Those with previous falls, as well as those with gait or balance disorders, are most at risk.
Complications In addition to susceptibility to fractures, osteoporosis can lead to other complications. Bone fractures from osteoporosis can lead to disability and an increased risk of death after the injury in elderly people. Osteoporosis can decrease the quality of life, increase disabilities, and increase the financial costs to health care systems.
Risk factors
The risk of having osteoporosis includes age and sex. Risk factors include both non-modifiable (for example, age and some medications that may be necessary to treat a different condition) and modifiable (for example, alcohol use, smoking, and vitamin deficiency). In addition, osteoporosis is a recognized complication of specific diseases and disorders. Medication use is theoretically modifiable, although in many cases, the use of medication that increases osteoporosis risk may be unavoidable. Caffeine is not a risk factor for osteoporosis. White people have a higher risk for the disease.
Non-modifiable
The most important risk factors for osteoporosis are advanced age (in both men and women) and female sex; estrogen deficiency following menopause or surgical removal of the ovaries is correlated with a rapid reduction in bone mineral density, while in men, a decrease in testosterone levels has a comparable (but less pronounced) effect. Ethnicity: While osteoporosis occurs in people from all ethnic groups, European or Asian ancestry predisposes to osteoporosis. Heredity: Those with a family history of fracture or osteoporosis are at an increased risk; the heritability of fracture risk is 50–70%, whereas the heritability of low bone mineral density is around 60–80%. Hundreds of distinct locations on DNA have been identified as being associated with increased risk. Those who have already had a fracture are at least twice as likely to have another fracture compared to someone of the same age and sex. Build: A small stature is also a non-modifiable risk factor associated with the development of osteoporosis.
Potentially modifiable Alcohol: Alcohol intake may increase the risk of osteoporosis. People who consume 0.5-1 drinks a day may have 1.38 times the risk compared to people who do not consume alcohol, while people who drink 2 or more glasses a day may have 1.63 times the risk. Vitamin D deficiency: Low circulating Vitamin D is common among the elderly worldwide. Mild vitamin D insufficiency is associated with increased parathyroid hormone (PTH) production. PTH increases bone resorption, leading to bone loss. A positive association exists between serum 1,25-dihydroxycholecalciferol levels and bone mineral density, while PTH is negatively associated with bone mineral density. Tobacco smoking: Many studies have associated smoking with decreased bone health, but the mechanisms are unclear. Tobacco smoking has been proposed to inhibit the activity of osteoblasts, and is an independent risk factor for osteoporosis. Smoking also results in increased breakdown of exogenous estrogen, lower body weight and earlier menopause, all of which contribute to lower bone mineral density. Malnutrition: Nutrition has an important and complex role in the maintenance of good bone. Identified risk factors include low dietary calcium, phosphorus, magnesium, zinc, boron, iron, fluoride, copper, vitamins A, K, E, and C (and vitamin D, where skin exposure to sunlight provides an inadequate supply). Excess sodium is a risk factor. High blood acidity may be diet-related and is a known antagonist of bone. Imbalance of omega-6 to omega-3 polyunsaturated fats is yet another identified risk factor. A 2017 meta-analysis of published medical studies shows that a higher protein diet helps slightly with lower spine density but does not show significant improvement with other bones. A 2023 meta-analysis sees no evidence for the relation between protein intake and bone health. Underweight/inactive: Bone remodeling occurs in response to physical stress, so physical inactivity can lead to significant bone loss. Weight bearing exercise can increase peak bone mass achieved in adolescence, and a highly significant correlation between bone strength and muscle strength has been determined. The incidence of osteoporosis is lower in overweight people. Endurance training: In female endurance athletes, large volumes of training can lead to decreased bone density and an increased risk of osteoporosis. This effect might be caused by intense training suppressing menstruation, producing amenorrhea, and it is part of the female athlete triad. However, for male athletes, the situation is less clear, and although some studies have reported low bone density in elite male endurance athletes, others have instead seen increased leg bone density. Heavy metals: A strong association between cadmium and lead with bone disease has been established. Low-level exposure to cadmium is associated with an increased loss of bone mineral density readily in both genders, leading to pain and increased risk of fractures, especially in the elderly and in females. Higher cadmium exposure results in osteomalacia (softening of the bone). Soft drinks: Some studies indicate soft drinks (many of which contain phosphoric acid) may increase risk of osteoporosis, at least in women. Others suggest soft drinks may displace calcium-containing drinks from the diet rather than directly causing osteoporosis. Proton pump inhibitors (such as lansoprazole, esomeprazole, and omeprazole), which decrease the production of stomach acid, are a risk factor for bone fractures if taken for two or more years, due to decreased absorption of calcium in the stomach.
Medical disorders