Your go-to guide about the disease that causes low bone density.
Osteoporosis literally means "porous bones" and is a disease that causes low bone density, making bones fragile and more likely to break. It happens when bones lose critical nutrients like calcium and phosphorus that are required to make them strong. While osteoporosis affects all bones, the majority of bone fractures occur in the hip, wrist, and spine.
Osteoporosis can occur in people of any age or sex but it occurs most often in postmenopausal women. The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) estimates that ten million people in the United States have osteoporosis and another 34 million have reduced bone mass called osteopenia that puts them at risk for osteoporosis. About twice as many women as men are affected by low bone mass and osteoporosis.
Osteoporosis is often called a silent disease because it may have not any symptoms until you break a bone. While a person with osteoporosis may fracture a bone in a minor fall, someone with severe osteoporosis can get fractures simply by stepping off a curb or sneezing. Fractures may not be obvious and instead may manifest as pain or they may occur with no pain at all. Some symptoms that may be caused by osteoporosis include:
-- Severe back pain caused by collapsed vertebra.
-- Loss of height with accompanying stooped posture or other spinal deformities.
-- Fractures of the vertebrae, wrists, hips or other bones.
Bones are made up of cells, protein, and minerals. The presence of minerals, chiefly calcium and phosphorus, make the bone rigid. The more calcium and phosphorus you have in your bones, the larger and more dense they are. If these minerals are lost from bone, the bone becomes weaker and is more prone to fracture. When the loss of minerals is minor, it is called osteopenia and when it severe, it is called osteoporosis.
What causes mineral loss? From birth to death, bones are constantly undergoing a process of remodeling in which portions of the bone are broken down (called resorption) and then built back up again. Each bone in your body is completely turned over once every two to three months or so. Typically, before the age of 30 the rate of bone formation is higher than the rate of resorption so your bones increase in density. After bone mass peaks around the age of 30, the rate of resorption begins to exceed the rate of bone formation and so the bones lose mass.
The rate of bone loss is slowed considerably by the sex hormones testosterone and estrogen. In women, the onset of menopause that occurs around age 50 causes a rapid decline in the levels of estrogen in the body, greatly accelerating bone loss. Women can lose up to 20 percent of their bone mass in the five to seven years after menopause making them susceptible to osteoporosis. While testosterone levels also decline in men as they age, the decline is more prolonged. This difference largely accounts for why women are much more likely than men to experience bone loss and osteoporosis.
Besides the changes in hormone levels that probably cause most cases of osteoporosis, some other possible causes include:
-- Being confined to a bed.
-- Bone cancer.
-- Cushing syndrome.
-- Long-term use of corticosteroid drugs for conditions such as asthma, arthritis, skin diseases, and COPD.
-- Thyroid problems.
-- Inadequate intake of calcium or vitamin D (which helps you absorb calcium from your diet).
Researchers estimate that about 1 out of 5 American women over the age of 50 have osteoporosis. About half of all women over the age of 50 will suffer a fracture of the hip, wrist, or vertebra (bones of the spine).
Risk factors for osteoporosis include:
-- Sex: Women are at least twice as likely to have osteoporosis as men because they have less bone mass to begin with and lose bone mass faster than men as they age. About 1 out of 5 American women over the age of 50 have osteoporosis.
-- Age: The older you are, the greater your risk of osteoporosis. The longer it has been since your bone density peaks in your thirties, the thinner and weaker your bones become.
-- Body size: Small, thin-boned people (especially women) are at greater risk.
-- Ethnicity: Caucasian and Asian women are at highest risk while African American and Hispanic women have a lower risk.
-- Family history: People who have close relatives with low bone mass, osteoporosis, or a history of fractures may be at higher risk.
-- Sex hormone levels: Low estrogen levels in women and low testosterone levels in men can bring on osteoporosis. It is lifetime exposure that matters so women with infrequent menstrual periods or early menopause are at increased risk.
-- Calcium and vitamin D intake: A diet low in calcium and vitamin D makes you more prone to bone loss and osteoporosis.
-- Medications: Long-term use of corticosteroids can lead to loss of bone density.
-- Lifestyle: a sedentary lifestyle or extended bed rest causes reduced bone mass.
-- Cigarette smoking: Cigarettes increase the risk of bone problems.
-- Alcohol intake: Excessive alcohol consumption increases the risk of bone loss.
-- Having osteopenia: Osteopenia is like pre-osteoporosis and often progresses to become osteoporosis unless it is treated.
Determining if you have osteoporosis or osteopenia requires a bone mineral density (BMD) test. If you are a post-menopausal woman, you may want to consider having such a test because osteopenia and osteoporosis often have no symptoms.
The best bone mineral density test is called dual energy X-ray absorptiometry (DEXA). The test is quick, painless, and very accurate. It measures the bone density in the hip, spine, and wrist and can be used to track changes in the density at these sites over time. Other tests that can measure bone density include ultrasound and computerized tomography (CT) scanning.
Treatment for osteoporosis usually includes changes in nutrition, an exercise regimen, and medications that help slow bone loss. It is important to make sure you get enough calcium and vitamin D in your diet to help maintain the bone density you have. Exercise, especially weight-bearing exercise such as walking or jogging is important because it helps stimulate new bone growth and increases muscle strength. Because of the danger of fractures, osteoporosis patients should consult a doctor about how to exercise without putting sudden or excessive strain on your bones.
Medications to treat osteoporosis or prevent osteopenia from progressing to osteoporosis include:
-- Hormone therapy: For post-menopausal women, replacing lost estrogen can help slow the process of bone loss. Some types of hormone therapy have been found to increase the risk of certain types of cancers and studies are underway to determine how to make hormone replacement as safe as possible. Talk to your doctor about the available options for hormone therapy and which one may be right for you.
-- Bisphosphonates: This class of drugs works by inhibiting the process of bone resorption, thus slowing the process of bone loss and even increasing bone density in some areas. Drugs in this class include Alendronate (Fosamax), risedronate (Actonel), ibandronate (Boniva), and zoledronic acid (Reclast). They are all approved for the treatment of postmenopausal osteoporosis while Risedronate is also approved to prevent and treat glucocorticoid-induced osteoporosis and to treat osteoporosis in men.
-- Raloxifene (Evista): This medication mimics the effects of estrogen in the bones and can help post-menopausal women maintain bone density without the increased cancer risk that comes with hormone therapy.
-- Calcitonin: This is a hormone normally produced only in small amounts by the adult thyroid gland. It inhibits the process of bone resorption and can slow bone loss, but is less effective than the bisphosphonates.
-- Teriparatide (Forteo): This drug is a synthetic version of normal body hormone called parathyroid hormone. Instead of blocking bone resorption, it works by stimulating new bone growth.
-- Tamoxifen: This synthetic hormone is used to treat breast cancer but it also has an estrogen-like effect your bone cells, maintaining bone density.
Another step you can take is making safety modifications around your home and workplace to help prevent falls that could cause fractures.
Probably the most important factor in preventing osteoporosis is making sure you get enough calcium and vitamin D (which helps you absorb calcium). This is important throughout your life, not just when bone density starts to decline after age 30 or so. In fact, it is most important when the body's demand for calcium is greatest including childhood, adolescence, during pregnancy, and breast-feeding.
Other things you can do to prevent osteoporosis include:
-- Get enough exercise.
-- Add soy to your diet.
-- Don't smoke.
-- Consider hormone therapy if you are post-menopausal.
-- Limit alcohol intake.
-- Avoid excessive caffeine consumption.
Early detection is important in the successful treatment of osteoporosis. Talk with your doctor about a prevention strategy that includes regular screening. If you're a woman, the National Osteoporosis Foundation recommends that you have a bone mineral density (BMD) test if you aren't taking estrogen and you:
-- Are older than age 65
-- Are postmenopausal and have at least one risk factor for osteoporosis
-- Have a vertebral abnormality
-- Use corticosteroid medications (e.g. prednisone) that can cause osteoporosis
-- Have type 1 diabetes, liver disease, kidney disease, thyroid disease, or a family history of osteoporosis
-- Experienced early menopause