Osteoporosis is a bone disease that develops when bone mineral density and bone mass decreases, or when the quality or structure of bone changes. This can lead to a decrease in bone strength that can increase the risk of fractures (broken bones).

Osteoporosis is a “silent” disease because you typically do not have symptoms, and you may not even know you have the disease until you break a bone. Osteoporosis is the major cause of fractures in postmenopausal women and in older men. Fractures can occur in any bone but happen most often in bones of the hip, vertebrae in the spine, and wrist.

However, you can take steps to help prevent the disease and fractures by:

• Staying physically active by participating in weight-bearing exercises such as walking.
• Drinking alcohol in moderation.
• Quitting smoking, or not starting if you don’t smoke.
• Taking your medications, if prescribed, which can help prevent fractures in people who have osteoporosis.
• Eating a nutritious diet rich in calcium and vitamin D to help maintain good bone health.

Although osteoporosis can strike at any age, it is most common among older people, especially older women. Men also have this disease. White and Asian women are most likely to have osteoporosis. Other women at great risk include those who:

• Have a family history of broken bones or osteoporosis
• Have broken a bone after age 50
• Had surgery to remove their ovaries before their periods stopped
• Had early menopause
• Have not gotten enough calcium and/or vitamin D throughout their lives
• Had extended bed rest or were physically inactive
• Smoke (smokers may absorb less calcium from their diets)
• Take certain medications, including medicines for arthritis and asthma and some cancer drugs
• Used certain medicines for a long time
• Have a small body frame

The risk of osteoporosis grows as you get older. At the time of menopause, women may lose bone quickly for several years. After that, the loss slows down but continues. In men, the loss of bone mass is slower. But, by age 65 or 70, men and women are losing bone at the same rate.

A new study linked 32 novel genetic regions to bone mineral density. The findings may help researchers understand why some people are more susceptible to bone fractures. The research also points to potential drug targets for preventing or treating osteoporosis.

Bones are made of a mineral and protein scaffold filled with bone cells. Bone is continually broken down and replaced. When the rate of bone loss outpaces the rate of replacement, bones weaken, eventually leading to osteoporosis and increased risk of fracture. More than 40 million people nationwide either have osteoporosis or are at increased risk for broken bones because of low bone mineral density (osteopenia).

Past studies suggest that genetic differences may account for more than half the variance in bone mineral density between people. Previous genome-wide association studies identified 24 genetic regions that influence bone mineral density. However, these genetic variants explained a small fraction of the variation in bone density, and none were shown to influence the risk of fracture in a definitive way.

A worldwide consortium with multiple research groups set out to do the largest search to date for variants related to bone mineral density. The effort was funded by many sources, including the European Commission and several NIH components, such as the National Institute on Aging (NIA) and National Institute for Arthritis, Musculoskeletal and Skin Diseases (NIAMS). The extensive research team—led by a group at Erasmus Medical Center in Rotterdam, the Netherlands—also included scientists at NIA. The study appeared online in Nature Genetics on April 15, 2012.

The researchers first combined data from 17 different studies involving more than 80,000 people across North America, Europe, East Asia and Australia. They looked across the genome for genetic variants associated with bone mineral density of the femoral neck and lumbar spine. The researchers found 96 independent variations from 87 genomic regions.

The scientists next tested these associations in over 50,000 more people from 34 other studies. They confirmed the association with bone mineral density in 56 regions, 32 of which hadn't been previously been tied to bone density.

The team also examined whether the 96 variants were associated with bone fractures. They analyzed data from 50 studies with fracture information. Combined, the studies involved over 31,000 people with fractures and over 102,000 controls. Fourteen of the regions, the researchers found, were also associated with bone fracture risk.

These findings reinforce the relationship between genetic factors and the risk of osteoporosis and bone fracture. However, the researchers found that the ability to use these factors to predict risk was modest relative to clinical risk factors such as age and weight.

“In reality, there may be 500 or more gene variants regulating osteoporosis,” says Dr. John Ioannidis of the Stanford University School of Medicine, one of the senior authors. “Each variant conveys a small quantum of risk or benefit. We can't predict exactly who will or won't get a fracture.”

“The ultimate goal of genetic studies like this is to develop personal, gene-based treatments for osteoporosis as well as to better identify those at high risk for the disease,” says another of the senior authors, Dr. Douglas P. Kiel of Harvard Medical School. “The findings could lead to new therapies to prevent or treat osteoporosis.”

—by Harrison Wein, Ph.D.

Osteoporosis is not just a woman’s disease. Not as many men have it as women do, maybe because most men start with more bone density. As they age, men lose bone density more slowly than women. But, men need to be aware of osteoporosis.

Experts don’t know as much about this disease in men as they do in women. However, many of the things that put men at risk are the same as those for women, including family history, not enough calcium or vitamin D, and too little exercise. Low levels of testosterone, too much alcohol, taking certain drugs, and smoking are other risk factors.

Older men who break a bone easily or are at risk for osteoporosis should talk with their doctors about testing and treatment.

If one of your parents has had a broken bone, especially a broken hip, you may need to be screened earlier for osteoporosis. This is a medical condition where bones become weak and are more likely to break. Share your family health history with your doctor. Your doctor can help you take steps to strengthen weak bones and prevent broken bones.

How can osteoporosis affect my health?

People with osteoporosis are more likely to break bones, most often in the hip, forearm, wrist, and spine. While most broken bones are caused by falls, osteoporosis can weaken bones to the point that a break can occur more easily, for example by coughing or bumping into something. As you get older, you are more likely to have osteoporosis and recovering from a broken bone becomes harder. Broken bones can have lasting effects including pain that does not go away. Osteoporosis can cause the bones in the spine to break and begin to collapse, so that some people with it get shorter and are not able to stand up straight. Broken hips are especially serious—afterward, many people are not able to live on their own and are more likely to die sooner.

How can I find out if I have osteoporosis?

Osteoporosis is more common in women. It affects about 25% (1 in 4) of women aged 65 and over and about 5% (1 in 20) of men aged 65 and over. Many people with osteoporosis do not know they have it until they break a bone. Screening is important to find these people before this happens, so they can take steps to decrease the effects of osteoporosis.

Currently, screening for osteoporosis is recommended for women who are 65 years old or older and for women who are 50 to 64 and have certain risk factors, which include having a parent who has broken a hip. Talk to your doctor if you have concerns about osteoporosis.

Screening for osteoporosis is commonly done using a type of low level x-rays called dual/energy x-ray absorptiometry (DXA). Screening also can show if you have low bone mass, meaning your bones are weaker than normal, and are likely to develop osteoporosis.

How can I improve my bone health if I have osteoporosis?

There are steps you can take to improve your bone health and strengthen weak bones:

• Take medications to strengthen your bones and avoid medications that can make your bones weaker.
• Eat a healthy diet that includes adequate amounts of calcium and vitamin D.
• Perform weight-bearing exercises regularly.
• Do not smoke.
• Limit alcohol use.

Don’t wait until you have a broken bone to take steps to improve your bone health—you can start at any age! You can also take steps to prevent falls, including doing exercises to improve your leg strength and balance, having your eyes checked, and making your home safer.

Strong bones are important for your health. A bone mineral density (BMD) test is the best way to measure your bone health. It compares your bone density, or mass, to that of a healthy person who is the same age and sex as you are. It can show:

• Whether you have osteoporosis, a disease that makes your bones weak
• Your risk for breaking bones
• Whether your osteoporosis treatment is working

Low bone mass that is not low enough to be osteoporosis is sometimes called osteopenia. Causes of low bone mass include family history, not developing good bone mass when you are young, and certain conditions or medicines. Not everyone who has low bone mass gets osteoporosis, but they are at higher risk for getting it.

If you have low bone mass, there are things you can do to help slow down bone loss. These include eating foods rich in calcium and vitamin D and doing weight-bearing exercise such as walking, tennis, or dancing. In some cases, your doctor may prescribe medicines to prevent osteoporosis.

What is a bone mineral density test?

A bone mineral density (BMD) test measures calcium and other minerals in bone. Bones containing more minerals are denser, so they tend to be stronger and less likely to break.

Bones can become less dense as we age or if we develop certain medical conditions. When too much bone is lost, osteoporosis can develop. Osteoporosis causes bones to become weak and brittle, which increases the risk of fractures (broken bones).

Bone mineral density testing can:

• Identify and diagnose osteoporosis.
• Measure the risk of fractures (broken bones).
• Monitor the effectiveness of osteoporosis treatment.

What tests are used to measure bone mineral density?

The most common bone mineral density test is a central dual energy x-ray absorptiometry (DXA or DEXA). DXA uses radiation to measure how much calcium and other minerals are in a specific area of your bone. Because the weak bones that tend to break most often are the hip and spine, DXA usually measures bone mineral density in these bones.

Other tests can also measure bone mineral density or bone loss:

• Quantitative ultrasound (QUS) of the heel: Shows pictures of your bone and can predict your risk of broken bones and osteoporosis. But it is not used to monitor response to osteoporosis treatment, and it does not measure bone mineral density or give as much information as DXA. If the QUS shows that you have a higher risk of osteoporosis or broken bones, your doctor may recommend a central DXA test to confirm the finding.
• Peripheral DXA: Measures bone mineral density, usually in the wrist and heel, using a portable device. This test does not give as much information as central DXA, so it is less accurate. Results showing a higher risk of broken bones or osteoporosis may need to be confirmed with a central DXA test.

What is a T-score?

If you are a woman in postmenopause or a man who is age 50 or older, your bone mineral density test result will be a T-score.

A T-score is the difference between your bone mineral density and 0, which is the bone mineral density of a healthy young adult.

The lower your T-score, the higher your risk of bone fracture.

What does a T-score mean?

If your T-score is:

• 1 or higher, your bone is healthy.
• –1 to –2.5, you have osteopenia, a less severe form of low bone mineral density than osteoporosis.
• –2.5 or lower, you might have osteoporosis.

The risk of broken bones increases by 1.5 to 2 times with each 1-point drop in the T-score.

What is a Z-score?

If you are a premenopausal woman or a man younger than age 50, your bone mineral density test result will be a Z-score. Z-scores are also used for children.

The Z-score is the difference between your bone mineral density and the average bone mineral density for healthy people of your age, ethnicity, and sex.

What does a Z-score mean?

If your Z-score is –2.0 or less, your bone mineral density is low. This score could mean that you have osteoporosis caused by medications or other diseases and conditions.

Who should get a bone mineral density test?

The U.S. Preventive Services Task Force recommends that women over age 65 have a bone mineral density test. The Task Force also recommends this screening for women of any age who have factors, identified by a health care provider who uses a formal risk-assessment tool, that raise their chance of osteoporosis.

More research is needed before the U.S. Preventive Services Task Force can make a recommendation regarding osteoporosis screening in men or how often premenopausal women and women with risk factors should be screened.

What other tools can measure risk of fractures?

Bone mineral density measurement tests are not the only tools that doctors use to predict your risk of fractures.

Doctors may use the Fracture Risk Assessment Tool (FRAX) to estimate risk for fracture. This score uses your age, sex, medical history, country, and other factors. This information, along with your bone mineral density test results, can help health care providers understand your risk for fracture and can guide treatment. For people with osteoporosis or osteopenia, the FRAX score can predict the chances of a major fracture in the next 10 years. The FRAX score can also screen women in postmenopause younger than age 65 for osteoporosis risk.

What steps should I take after my test?

It is important that you review your BMD test results with your doctor for a full explanation of what they mean for you. Any diagnoses or treatment recommendations would be based on your BMD test results, age, and other fracture risk factors that you may have. In some cases, your doctor may refer you to a specialist.

Experts say that older women should have regular bone density tests to screen for osteoporosis. But it’s been unclear how often to repeat the tests. A new study suggests that women with healthy bone density on their first test might wait 15 years before getting rescreened.

More than 40 million people nationwide either have osteoporosis or are at increased risk for broken bones because of low bone mineral density (osteopenia). Osteoporosis is often called a “silent disease” because it usually develops slowly and without symptoms until a fracture occurs.

When early screening detects low bone mineral density, patients can try lifestyle changes or therapies to protect their bones.

To help develop guidance on how often to repeat bone density tests, NIH-funded scientists studied nearly 5,000 women ages 67 and older. When the study began, none of the women had osteoporosis, hip or spine fractures or past treatment with osteoporosis medications.

The researchers found that less than 1% of women who initially had normal bone mineral density went on to develop osteoporosis during the study. Only 5% of those with mildly low bone density at the start made the transition to osteoporosis.

“If a woman’s bone density at age 67 is very good, then she doesn’t need to be rescreened in 2 years or 3 years, because we’re not likely to see much change,” says lead researcher Dr. Margaret Gourlay of the University of North Carolina at Chapel Hill. “Our study found it would take about 15 years for 10% of women with normal or mildly low bone mineral density to develop osteoporosis. That was longer than we expected, and it’s great news for this group of women.”

Age, past fractures, medications and specific diseases can increase osteoporosis risk. These factors also affect how often a woman should be tested.

Osteoporosis is a bone disease that makes bones weaker and more likely to break. Anyone can get osteoporosis, but it’s most common in older women.

Ask your doctor or nurse about steps you can take to prevent weak bones and lower your risk for osteoporosis. If you're a woman age 65 years or older, schedule a bone density test. And if you're age 64 years or younger and you've gone through menopause, ask your doctor if you need to get a bone density test.

What do I ask the doctor?

When you visit the doctor, it helps to have questions ready ahead of time. You can also ask a family member or friend to go with you to take notes.

Consider taking this list of questions to your next appointment.

• Am I at risk for osteoporosis?
• What puts me at risk for osteoporosis?
• What can I do to help prevent osteoporosis?
• How can I help prevent falls and injuries?
• Do any of my medicines cause bone loss?
• How much calcium and vitamin D do I need each day?
• Do you recommend that I get a bone density test?
• If I have osteoporosis, what are my treatment options?
• Can you give me some information about osteoporosis to take home with me

DEXA (dual x-ray absorptiometry) scans measure bone density (thickness and strength of bones) by passing a high and low energy x-ray beam (a form of ionizing radiation) through the body, usually in the hip and the spine. This procedure is important for diagnosing (seeing if someone has) osteoporosis or bone thinning and may be repeated over time to track changes in bone density.

The amount of radiation used in DEXA scans is very low and similar to the amount of radiation used in common x-rays. Although we all are exposed to ionizing radiation every day from the natural environment, added exposures can slightly increase the risk of developing cancer later in life.

What You Should Know

Your healthcare provider may recommend a DEXA scan to test for osteoporosis or thinning of your bones.

Screening for osteoporosis is recommended for women who are 65 years old or older and for women who are 50 to 64 and have certain risk factors, such as having a parent who has broken a hip. However, there are other risk factors for osteoporosis besides age and gender, such as some intestinal disorders, multiple sclerosis, or low body weight. Your healthcare provider may recommend a DEXA scan if you have any of these other risk factors. DEXA scans should be used when the health benefits outweigh the risks. Talk to your healthcare provider about any concerns you have before a DEXA scan.

• Nearly 1 in 5 women and 1 in 20 men over the age of 50 are affected by osteoporosis.
• Osteoporosis increases the risk for broken bones and can have serious effects in older adults.

What To Expect

Before the procedure

• Make sure to let your healthcare provider or radiologist (medical professional specially trained in radiation procedures) if you are pregnant or think you may or could be pregnant.
• Dress in loose, comfortable clothing. Don’t wear anything that has metal on it like buckles, buttons, or zippers. Metal can interfere with test results.

During the procedure

• You may be asked to remove jewelry, eyeglasses, and any clothing that may interfere with the imaging.
• You will lay on a table and the radiologist or medical assistant will position your legs on a padded box. They also may place your foot in a device so that your hip is turned inward.
• While the image is taken, lay still and follow instructions. You may need to hold your breath for a few seconds.

After the procedure

• The procedure typically lasts about 15-20 minutes.
• Your healthcare provider will follow up with you with your results. They will show a T-score and a Z-score. The T-score shows how your bone density compares to the optimal peak bone density for your gender. The Z-score shows how your bone density compares to the bone densities of others who are the same age, gender, and ethnicity.

Benefits and Risks of DEXA Scans

DEXA scans are different from other imaging procedures because they are used to screen for a specific condition.

Benefits:

• Detects weak or brittle bones to help predict the odds of a future fracture
• Determines if bone density is improving, worsening, or staying the same
• Can help you and your healthcare provider come up with plans to improve your bone strength and prevent worsening conditions

Risks:

• A very slight increase in possibility of future cancer, similar to the risks from x-rays.