Osteoporosis

Osteoporosis is a condition characterized by decreased bone density. As bones become less dense, bone strength is compromised and the risk of fracture increases.


Causes/associated factors
As living tissue, bone renews and repairs itself. Hormones regulate this process by controlling the activity of two types of cells: osteoclasts and osteoblasts. Osteoclasts break bone down, and osteoblasts build it back up. Until you're about 30 years old, calcium intake helps your body strengthen bone density. Eventually, however, the balance of osteoclast and osteoblast activity changes, and the ability to absorb calcium begins to decrease. These changes often lead to the silent process of bone loss. Osteoporosis can also develop if optimal or peak bone mass is not reached during childhood and adolescence.
Osteoporosis is a common condition that can affect both men and women. However, women are five times more likely than men to develop osteoporosis because they have less bone and because of the hormonal changes of menopause. More than 50 percent of all women eventually develop osteoporosis-related fractures. Before menopause, the hormone estrogen helps retain the calcium in women's bones. With menopause, the ovaries stop producing estrogen, and bones begin to lose up to 3 percent of their calcium per year. This loss is especially rapid in the first few years after menopause.

Risk factors
Various factors may increase your risk of developing osteoporosis, including:

being female, especially after menopause
thin, small bone frame or low body weight
advanced age
poor health or frailty
Caucasian or Asian descent
family history of osteoporosis or fractures
lifelong diet low in calcium and vitamin D
anorexia
physical inactivity
excessive alcohol (2 to 3 ounces or more a day) or caffeine intake
smoking cigarettes
for women, low estrogen levels
for men, low testosterone levels
Certain medications can also contribute to decreased bone mass, including some anticonvulsants, long-term heparin use, excessive use of antacids containing aluminum, high doses of thyroid medication and corticosteroids, and long-term steroid use. Finally, certain medical conditions can also lead to osteoporosis, including endocrine disorders (such as an overactive thyroid), gastrointestinal diseases, genetic disorders and kidney failure.


Signs/symptoms
Fractures are the main symptom of osteoporosis. Related symptoms may include:
back, hip or wrist pain
scoliosis (abnormal curvature of the spine)
stooped posture
loss of height
impaired mobility

Diagnosis
The doctor will ask questions about your medical history and do a physical exam. You may need certain blood tests. Because osteoporosis does not appear on a conventional X-ray until the condition is advanced, bone mass measurements -- also known as bone mineral density (BMD) studies -- may also be recommended. These studies can help the doctor:
detect osteoporosis before a fracture occurs
predict your risk of having a future fracture
determine your rate of bone loss
confirm a diagnosis and possible need for treatment
monitor the effects of treatment at certain intervals

Guidelines for bone mineral density testing
In collaboration with multidisciplinary physician organizations, the National Osteoporosis Foundation recommends BMD studies for:
women over age 65, regardless of other risk factors
postmenopausal women with one or more risk factor other than menopause for osteoporosis-related fractures, as well as a history of fractures as an adult and/or in a first-degree relative (a sister, mother or daughter), dementia, impaired eyesight despite adequate correction and recurrent falls
postmenopausal women who have fractures (to confirm the diagnosis and determine the severity of the disease), especially fractures of the hip or vertebrae (the bony sections that make up the spine)
women who have been on hormone replacement therapy for an extended period of time
women who are considering treatment for osteoporosis if the measurements would help in the decision-making process
The World Health Organization (WHO) and American Association of Clinical Endocrinologists recommend BMD studies for people who regularly take steroids or other drugs associated with bone loss or have chronic diseases associated with osteoporosis (such as hyperthyroidism or hyperparathyroidism). BMD studies may also be recommended by your doctor on an individual basis according to your particular risk factors.

BMD studies are typically considered unnecessary for healthy women on estrogen replacement therapy. If you're a woman past menopause not on estrogen replacement therapy, discuss bone mineral density testing with your doctor.


Techniques
Techniques for bone mass measurements may vary depending on your clinical situation.
Dual energy X-ray absorptiometry (DEXA or DXA) is the most accurate test available, detecting as little as a 1 percent bone loss. For this test, you lie on a padded platform while a wand-like device called an imager is passed over your body. DEXA takes about 10 minutes or less. The amount of radiation exposure during this test is a fraction of the amount in a standard chest X-ray.

Single photon absorptiometry (SPA) and dual photon absorptiometry (DPA) both use a radioactive material to detect bone loss. Both are less accurate and have higher radiation exposure than DEXA.

With quantitated computerized tomography (QCT), a computed tomography scanner (used to create a computer-generated, cross-sectional picture of internal body parts) with enhanced measurement abilities measures bone mineral density in any part of the body. QCT has a higher radiation exposure than DEXA.

The new device pDEXA (p for portable) is a smaller version of the DEXA device. This device measures bone mineral density in the finger, wrist or heel. Bone loss in the hip or spine, which is the best predictor of potential spinal or hip fractures, may not always be reflected.

Other devices (such as quantitative ultrasound and radiographic absorptiometry) measure bone mineral density in the hand and finger or heel. As with pDEXA, bone density testing at one body site may not necessarily indicate exact bone density at other locations.
Test results are compared to normal peak bone density (called a "T score"), which is thought to happen between ages 20 and 28. A 1 to 2.5 point deviation below normal bone density is diagnosed as osteopenia (reduced bone mass). A deviation of more than 2.5 points below normal is diagnosed as osteoporosis. Each standard deviation below the normal peak represents about a 10 to 12 percent loss of total bone mass.


Other bone studies
New biochemical markers known as bone turnover markers, which are categorized as either bone formation or bone resorption markers, are currently being studied for their use in helping doctors assess bone breakdown. The markers are found in both blood and urine. Test results may potentially provide information that supplements bone density measurements. Agreement on how these tests are best used has not yet been reached, however. The decision to use these tests is based on your specific circumstances.

Treatment
Although there is no cure for osteoporosis, a treatment plan can delay the onset and reduce the severity of the disease. Treatment typically includes adequate calcium and vitamin D intake, exercise and medication. Smoking cessation and prevention of falls are also important.
Calcium and vitamin D
If there isn't enough calcium in your blood, it will be taken from your bones. Vitamin D is also needed for calcium absorption in the intestines. Unfortunately, the ability to absorb calcium and produce vitamin D decreases with age.

Recommendations vary on adequate calcium intake. Some authorities recommend the following calcium intake for the treatment of osteoporosis:

1,500 milligrams for men and women over age 65 and postmenopausal women not taking estrogen
1,000 milligrams for postmenopausal women taking estrogen replacement therapy
1,000 milligrams for men under age 65
Normally, you produce enough vitamin D in your skin after about 20 minutes of sun exposure a day. If you have low bone mineral density, or are elderly or housebound, you should get 400 to 800 international units (IU) of vitamin D a day.

Excellent food sources of calcium include dairy products, calcium- fortified orange juice, canned salmon and sardines with bones, and dark green leafy vegetables such as broccoli, collard greens and dried beans. Caffeine can slightly reduce calcium absorption, but you can compensate by adding 1 to 2 tablespoons of milk to your coffee. Food sources of vitamin D include fortified cereal and dairy products, eggs, fatty fish and liver.

If necessary, your doctor may recommend calcium and vitamin D supplements. It's best to take calcium in divided doses with meals to increase absorption. Calcium intake of more than 2,000 milligrams per day may increase the chance of developing kidney stones. If you have a history of kidney stones, your doctor may recommend calcium citrate instead. Massive doses of vitamin D can be harmful to your liver and actually increase bone loss, so it's important not to take more than 800 international units a day.

Exercise
Your doctor may recommend at least 20 minutes per day of age-appropriate weight-bearing activities, such as walking, jogging, tennis, hiking, stair climbing and bicycling. Exercises to strengthen and support your back and improve posture and balance may also be suggested. Although exercise alone cannot cure osteoporosis, it can help preserve bone mass as part of an overall treatment plan. To develop an exercise program, you may be referred to a physical therapist.

Medication
Medications may be prescribed to prevent or treat osteoporosis. All medications for osteoporosis, except parathyroid hormone, must be taken on a long-term basis because the bone density benefits stop soon after the medication is discontinued.

Estrogen: Estrogen helps maintain calcium in the bones. Estrogen therapy has been used to prevent bone loss at menopause or when ovarian function is lost. It's been given along with the hormone progesterone (combination hormone therapy) or alone. However, recent research indicates the risks may outweigh the benefits in preventing osteoporosis. The U.S. Food and Drug Administration recommends that estrogen be used only to treat the symptoms of menopause, rather than to prevent osteoporosis or other disease. And even then, it should be used in the smallest effective dose for the shortest possible time.

Benefits of estrogen: This hormone can significantly reduce the risk of fractures after menopause.

Risks of estrogen: The protective benefits of estrogen on bones does not continue once the medication is stopped. With combination hormone therapy, you are at increased risk of developing breast cancer or dementia, or having a heart attack, stroke, or blood clots in the lungs and legs. When estrogen is taken alone, you still may be at greater risk of having a stroke or developing blood clots in the legs or dementia. If you still have a uterus, taking estrogen by itself increases the risk of developing endometrial cancer (cancer of the tissue that lines the uterus). New research also shows that long-term estrogen use may increase the risk of developing ovarian cancer. Discuss the risks and benefits of estrogen therapy with your doctor. If you're taking estrogen replacement therapy, you'll need close medical supervision.
Selective estrogen receptor modulators (SERMs): A new classification of medications called selective estrogen receptor modulators (SERMs) mimic the effects of estrogen in certain body tissues. Raloxifene (brand name Evista) is a commonly prescribed SERM. During menopause, they may be used to prevent or treat osteoporosis.

Benefits of SERMs: These medications increase bone density, reduce the risk of bone fractures due to osteoporosis, and lower levels of fat in your blood. They don't affect breast or uterine tissue, so they don't increase your risk of cancer in these organs.

Risks of SERMs: These medicines may increase your risk of developing a blood clot in a vein, which can break off and travel to the lungs. Therefore, they're not recommended for women with a history of thrombophlebitis (inflammation of a vein caused by a blood clot in the vein). The most common side effects are hot flashes and leg cramps.
Biphosphonates: Biphosphonates are used during menopause to prevent and treat osteoporosis. Alendronate (Fosamax) and risedronate (Actonel) are commonly prescribed biphosphonates.

Benefits of biphosphonates: These medications increase bone density by inhibiting bone breakdown and slowing bone removal. They significantly decrease the risk of fractures. A once-a-week dose of alendronate is now available.

Risks of biphosphonates: These medications can cause irritation of the throat and esophagus, and must be taken on an empty stomach with 6 to 8 ounces of water. You must then remain upright and not eat or drink for at least 30 minutes. They are generally well tolerated. Side effects may include nausea, heartburn, abdominal pain and muscle pain.
Calcitonin: Calcitonin is a hormone naturally produced by the thyroid gland. Bone loss is triggered when calcitonin levels drop. To slow bone loss, calcitonin regulates bone metabolism and calcium levels in the blood. You can take calcitonin as a daily injection or through a nasal spray. Calcitonin is an option for postmenopausal women who can't take or tolerate other medications for osteoporosis.

Benefits of calcitonin: This medication may decrease the risk of fractures from osteoporosis.

Risks of calcitonin: Side effects may include facial flushing, nausea, frequent urination or rash. Allergic reactions are possible, but uncommon. You may have nasal irritation if you use the nasal spray or mild inflammation at the injection site.
Parathyroid hormone (PTH)
Parathyroid hormone has been shown to stimulate bone formation. Teriparatide (Forteo) is an injectable form of the hormone that has recently become available to treat postmenopausal women and men with osteoporosis who have a high risk of fractures. It's given by daily injection for up to two years.

Benefits of parathyroid hormone: Teriparatide stimulates new bone to form in the hip and the spine, and may reduce the risk of fractures. The benefits may continue after the medication is stopped.

Risks of parathyroid hormone: Side effects may include nausea, dizziness and leg cramps.
Smoking cessation
If you smoke, quitting is a vital part of osteoporosis treatment. To improve the odds of quitting, ask your doctor how to manage nicotine withdrawal. Behavior modification therapy or other strategies may be recommended.

Prevention of falls
As part of an osteoporosis treatment plan, it's important to prevent falls and minimize your risk of breaking a bone. Consider the following safety tips.

Wear flat, rubber soled shoes.
Use a cane or walker if necessary.
Install hand grips in the bathroom, and use a safety mat in the bathtub.
Make sure your hallways and stairwells are well lit.
Wear corrective lenses to improve your vision if necessary.
Avoid throw rugs and check your home for other tripping hazards, such as cords.
Exercise regularly to improve or maintain muscle strength, balance and coordination.
Do not lift heavy objects or stoop to pick up things. When you do pick up something, bend at the knees and keep your back straight as you lower your body.
Consult your doctor if you take medication that may put you at risk for falls, such as sedatives.

Complications
Fractures are the most common complication of osteoporosis. More than 50 percent of all women develop osteoporosis-related fractures at some point. Other possible complications may include:
severe, disabling pain
neurological problems from spinal fractures
disability or death from fracture complications

Pregnancy-specific information
Osteoporosis is rare in pregnancy. Inadequate calcium intake during pregnancy can contribute to bone density loss and osteoporosis. For healthy women, the adequate calcium intake is the same before, during and after pregnancy. Women age 19 and older need at least 1,000 milligrams of calcium a day (almost the amount of calcium found in 3 cups of milk). Women age 18 and younger need at least 1,300 milligrams of calcium a day.

Senior-specific information
Again, bones become less dense and more fragile as you age. The older you are, the more likely you are to develop osteoporosis.

Prevention
Optimal prevention begins early in adolescence and adulthood when bone can be deposited. Children from 9 to 18 years of age should get 1300 milligrams of calcium a day. Throughout life, eat a diet rich in calcium and vitamin D. Do regular weight-bearing exercises. Also avoid smoking and excessive alcohol intake. For women, estrogen replacement therapy may be helpful when natural estrogen production diminishes, but the risks and benefits of treatment must carefully considered. Consult your doctor for details.