What Is Osteoporosis?
Bone is made up of calcium and protein. There are two types of bone compact bone and spongy bone and each bone in the body contains some of each type. Compact bone looks solid and hard and is found on the outer part of bones. Spongy bone is filled with holes, like a sponge, and is found on the inside of bones. The first signs of osteoporosis are seen in bones with a lot of spongy bone, such as the spine, hip and wrist.
Once made, bone is always changing. Old bone is removed in a process called resorption, and new bone is formed in a process called formation. From childhood until age 30, bone is formed faster than it is broken down, and bones become large and more dense. After age 30, the process begins to reverse: Bone is broken down faster than it is made, a process that continues throughout life. A small amount of bone loss after age 35 is normal in all women and men, and usually doesn’t cause any problems. However, too much bone loss can result in osteoporosis, a condition in which bones become thin and brittle because more bone is lost than formed. The bones are still the same size, but the outside walls of compact bone become thinner, and the holes in spongy bone become larger, thus greatly weakening the bone.
Osteoporosis poses a special threat to women. The female hormone estrogen protects against bone loss, but as a woman nears menopause, her body produces less estrogen. Hormone therapy slows bone loss after menopause estrogen decreases the risk of hip fractures and spinal deformities, and progestin decreases the risk of endometrial cancer, which often occurs in women who have a uterus when estrogen is given alone.
However, bone loss begins long before menopause and a great deal of bone loss typically occurs before symptoms of osteoporosis show. These symptoms include back pain or tenderness, height loss and a slight curving of the upper back. As the spinal bones weaken, they slowly collapse under the weight of the upper body, causing a curving of the spine often called “dowager’s hump.”
Osteoporosis affects at least 10 million Americans, most of whom are women. More than 1.5 million osteoporosis-related fractures occur in the United States each year. Fifty percent of women older than 50 will experience such a painful and crippling fracture.
You should have a physical exam once a year in which your height is measured. All women age 65 and older, or younger women who have had a bone fracture, should be tested for bone mineral density no more than every two years. More frequent testing may be needed if new risk factors occur. Testing may be suggested for postmenopausal women younger than 65 who have one or more risk factors for osteoporosis.
Bone mineral density tests measure bone mass in the heel, spine, hip, hand or wrist to get a sense of bone density in other parts of your skeleton. The devices used for the tests vary, but all involve X-rays or beams from other energy sources. You may be asked to lie on your side or back for the X-ray, or you may sit and place your hand or foot in a cylinder. The tests, which can take anywhere from 1 to 40 minutes, can help detect problems before a fracture occurs and can help determine whether you have osteoporosis, your rate of bone loss and your risk of a future fracture. There are several ways to measure bone density all painless and safe.
Dual-Energy X-ray Absorptiometry (DXA)
DXA is typically used to measure the bone density of your spine or hip. It is the most accurate test currently available.
During the test, you lie down for 3 to 10 minutes while an arm-like device (an imager) scans your body. This test exposes you to a very small amount of radiation less than the amount in a normal chest X-ray.
After the test, you will be given a T-score, a number that is calculated by comparing your DXA test results to the bone density of an average healthy 30-year-old. A negative score means you have thinner bones than an average 30-year-old. A positive score means your bones are stronger and thicker than an average 30-year-old.
If your T-score is -1 to -2.5, you have low bone mass and are at increased risk for osteoporosis. A score of -2.5 or lower means you have osteoporosis. A low T-score may mean that you are at increased risk of a bone fracture. In rare cases, low T-scores are caused by other medical conditions.
Quantitative Computed Tomography (QCT)
This method uses both computed tomography scanning and computer software to test the bone density of the spine. This test provides three-dimensional images and requires only a little more radiation than a DXA test.
This test uses sound waves instead of radiation to measure bone density. During this test, you place your bare foot on the machine and sound waves are transmitted through your heel. Although this test may help predict the risk of fracture in your spine or hip, it often is not as accurate as other tests because bone mass is not the same in all areas of the body.
Bones go through a constant state of loss and regrowth. As a person ages, more bone loss occurs than bone growth. This can lead to a condition called osteoporosis, in which bones become thin and fragile and can easily fracture or break.
There are many treatment options available to help reduce the risk of fracture. Some need to be taken daily, some weekly, some monthly. Annual injections are also available. No matter what dosing method you choose, the earlier treatment is started, the better it works.
Bisphosphonates are medications used to prevent and treat osteoporosis. In cases of prevention, they are used to slow bone breakdown. To treat osteoporosis, they are used to help increase bone density and reduce the risk of fractures. These medications must be taken on an empty stomach. Although rare, side effects may include nausea, stomach pain and digestive problems.
Selective Estrogen Receptor Modulators
Women also can take a type of drug known as selective estrogen receptor modulators (SERMs) to help prevent or treat some of the bone problems that can occur during menopause. Raloxifene is a type of SERM that helps strengthen bone tissue.
SERMs may be a good choice for women who need protection from osteoporosis, but cannot or do not want to take hormone therapy. This may include:
- Women at risk of breast cancer
- Women who cannot tolerate the side effects of hormone therapy
- Women who do not need relief from symptoms of menopause
- Hormone Therapy
Starting estrogen at any time after menopause can help prevent bone loss. It can be a good choice for women who also have symptoms of menopause. However, it only protects bones for as long as you use it. When you stop taking hormone therapy, bone loss resumes. You and your doctor should decide whether this treatment is right for you.
Calcitonin is another medication used to slow bone breakdown. It can be given by injection or nasal spray. Parathyroid hormone may also be used to increase bone density and reduce the risk of fractures.
Women have a greater risk of developing osteoporosis than men because of menopause and because their bones are smaller and lighter than men’s bones. Certain medications (see below) and medical conditions increase the risk of osteoporosis. The following factors can increase the risk of fractures caused by osteoporosis:
- Personal history of fracture’Family history of osteoporosis
- Caucasian race
- Poor nutrition
- Low body weight
- Early menopause in women younger than 45 (Bone loss increases after menopause because the ovaries stop making estrogen, which protects against bone loss.)
- Removal of ovaries (If a woman has her ovaries removed before menopause, the sudden decrease in estrogen can result in rapid bone loss unless she takes a preventive treatment, such as estrogen.)
- Prolonged amenorrhea before menopause (more than 1 year)
- Diet low in calcium (lifelong)
- History of falls
- Lack of exercise
- Vision problems
- Certain medications
Medications and Osteoporosis
Women who take certain medications may be at increased risk for osteoporosis. These include:
- Drugs that suppress the immune system
- Excessive thyroid hormone
- Drugs that affect the adrenal gland and the pituitary gland
- Gonadotropin-releasing hormone (GnRH) agonists (medical therapy used to block the effects of certain hormones)
- Blood thinners
- Anti-cancer drugs
Prevention: Diet, Exercise and Avoiding Falls
It is hard to grow new bone after it is lost, so prevention is important. Slowing bone loss helps build strong bones. To prevent osteoporosis, try to build and keep as much bone as you can by doing weight-bearing exercises and choosing foods with enough calcium and vitamin D. After menopause, your doctor may suggest medication to protect against bone loss if your bones show signs of early osteoporosis.
Bone loss can increase if your diet is low in calcium. If there is too little calcium in the bloodstream, it will be taken from the bones to supply the rest of the body.
Good sources of calcium are dairy products, such as milk and yogurt, leafy green vegetables, nuts, seafood, and calcium-fortified juices and cereals. Yet most women do not consume enough calcium in their diets. In fact, many women only consume half of the calcium they need each day. If you’re not getting enough through your diet, you may need to take calcium supplements. Women younger than 50 need 1,000 mg of calcium a day; women 50 years and older need 1,200 mg of calcium a day. The National Institutes of Health recommends 1,500 mg of calcium per day for postmenopausal women who do not take hormone therapy an all women older than 65. Be aware, however, that your body can only absorb about 500 mg of calcium at one time. If you take more, try to divide it into two doses.
Calcium cannot be absorbed without vitamin D. Milk fortified with vitamin D, including lactose-free milk, is one of the best sources. Sunlight is another. Just 15 minutes of sunlight a day helps your skin produce vitamin D and activates vitamin D in your body. You also can use vitamin D supplements. The recommended daily amount of vitamin D is 10 micrograms for women ages 51 to 70 and 15 micrograms for women older than 70.
Exercise increases bone mass before menopause and slows bone loss after menopause. Just as muscles become stronger with regular exercise, so do bones. Bones are strengthened when the muscles pull on them. Bone loss will occur any time the bones are not used, and it becomes worse in people who are bedridden or inactive for a long time. Active women have higher bone density than women who do not exercise.
Most aerobic exercise is good for the heart and bones. To help prevent bone loss, do weight-bearing exercises, such as low-impact or step aerobics, brisk walking or tennis. Even walking several blocks each day will slow bone loss. A little bit of exercise is better than none at all. If you have questions about the best exercise program for you, talk with your doctor or a professional who knows about health and exercise.
Find out about a medically supervised weight loss program at Dr. Margie Corney’s office.
To reduce the risks of injuries from falls, women with osteoporosis should:
- Learn good posture
- Avoid twisting, bending and lifting
- Make their homes safe by removing throw rugs or using nonskid backings, making sure rooms are well lit, and using handrails by stairs and in the bathroom
- Check and correct vision and balance problems
- Review medications for side effects that may affect balance and stability