What is osteoporosis?

Osteoporosis, which means "porous bones," is a condition that causes formerly strong bones to gradually thin and weaken, leaving them susceptible to fractures. About 1.5 million fractures occur each year due to osteoporosis.

Although all bones can be affected by the disease, those of the spine, hip, and wrist are most likely to break. In elderly people, hip fractures can be particularly dangerous because the prolonged immobility required during the healing process often leads to blood clots or pneumonia, both of which can be fatal.

Of the estimated 10 million Americans affected by osteoporosis, at least 80% are women. Experts believe women are more susceptible because their bones tend to be lighter and less dense and because their bodies experience hormonal changes after menopause that appear to accelerate the loss of bone mass. In men, osteoporosis is uncommon until after the age of 70.

What causes it?

Although the exact cause of osteoporosis is unknown, the process by which the bone becomes porous is well understood. Early in life, bone is broken down and replaced continuously, a process known as bone remodeling. Bone mass peaks usually in the late 20s. Bone loss -- where bone breakdown is outpacing bone buildup -- occurs in the mid-30s. Bones begin to lose calcium, the mineral that makes them hard, faster than they can replace it. Less remodeling takes place and the bones begin to thin.

For women, the loss of bone density speeds up during the first five to seven years after menopause and then slows down again. Scientists believe that this rapid postmenopausal increase in bone loss is caused by a sharp decline in the body's production of estrogen, which appears to help keep calcium in the bones.

Although some loss of bone density is a natural part of aging, certain women are at higher risk than others for developing the very porous bones and the fractures associated with osteoporosis. Women who are thin or have a small frame, for example, are at higher risk, as are those who smoke, drink more than moderately, or live a sedentary lifestyle.

Women with a family history of osteoporosis and those who have had their ovaries removed, especially before age 40, are also more prone to the condition. White and Asian women are more frequently affected than African-American and Hispanic women.

Certain conditions that increase bone breakdown, such as kidney disease, Cushing's syndrome, and an overactive thyroid, can also lead to osteoporosis. Glucocorticoids, strong anti-inflammatory drugs used to treat conditions such as rheumatoid arthritis and asthma, also increase bone loss. Antiseizure drugs can do this as well. Prolonged immobility due to paralysis or illness can also cause bone loss.

What are the symptoms of osteoporosis?

A person is usually not aware they have osteoporosis until a fracture occurs.

But there are some symptoms:

• Backache
• A gradual loss of height and an accompanying stooped posture
• Fractures of the spine, wrists, or hips

Call Your Doctor If:

• You develop a backache or sudden severe back pain, which can indicate a spinal compression fracture caused by osteoporosis.
• Dental X-rays reveal a loss of bone in the jaw, which can be an early sign of osteoporosis.

How do I know if I have osteoporosis?

If your doctor suspects you have osteoporosis, he or she may measure you to check for a loss of height. The vertebrae are often the first bones affected, causing a loss in height of half an inch or more

Your doctor may also recommend that your bone density be measured. Although osteoporosis is sometimes diagnosed incidentally after an X-ray has been taken for a fracture or an illness, an ordinary X-ray does not reveal bone loss until at least 20% to 30% of the bone mass has disappeared, limiting its usefulness for early screening of the condition.

Diagnostic tools more likely to catch osteoporosis at an early stage include various forms of a technique called absorptiometry, which is specifically designed to measure bone density. A relatively new diagnostic tool known as quantitative computerized tomography is also an accurate method of measuring bone density anywhere in the body, but it uses higher levels of radiation than the other methods. Some facilities are also equipped with specialized ultrasound machines that can detect early signs of osteoporosis.

In addition to these bone measurement tests, you may be asked to supply blood or urine samples for analysis so that disease-related causes for the bone loss can be ruled out.

What are the treatments?

Because osteoporosis is difficult to reverse, prevention is the key to treatment.

Calcium is the cornerstone of treatment. Dietary calcium and supplements should total 1,500 mg per day. To help with the absorption of the calcium, vitamin D supplements should also be taken. A regular exercise program -- including weight-bearing exercises, such as walking and aerobics -- can help keep your bones strong and free of fractures.

Menopausal hormone therapy -- either estrogen alone or a combination of estrogen and progestin -- used to be used for prevention and treatment of osteoporosis. However, in July 2002, a landmark study revealed that hormone therapy increases the risk of breast cancer, heart disease, and stroke in some women. Hormone therapy is known to help preserve bone and prevent fractures, but is not generally recommended at this point for osteoporosis because the risks are thought to outweigh the benefits.

In women who have been on menopausal hormone therapy in the past and then stop it, the bone begins to thin again -- at the same pace as during menopause.

Evista is a drug that has some actions similar to estrogen, such as the ability to maintain bone mass. However, studies have shown that it doesn't increase the risk of breast or uterine cancers like estrogen. Evista can cause blood clots and often increases hot flashes.

Actonel and Fosamax treat osteoporosis by inhibiting cells that break down bone. There are strict ways to take these medications, since if taken incorrectly, they can lead to ulcers in the esophagus.

Calcitonin is another option. Calcitonin is a naturally occurring hormone that inhibits bone loss. It is available as a nasal spray or injection and is quite expensive. Undesirable side effects include nausea and skin rashes.

Forteo is a new medication used for the treatment of osteoporosis in postmenopausal women and men who are at high risk for a fracture. A synthetic form of the naturally occurring parathyroid hormone, Forteo is the first drug shown to stimulate new bone formation and increase bone mineral density. It is self-administered as a daily injection for up to 24 months. Side effects include nausea, leg cramps, and dizziness.

Nutrition and Diet

To ensure that people are getting enough calcium to build and maintain strong bones, doctors recommend eating plenty of calcium-rich foods, such as nonfat milk, low-fat yogurt, broccoli, cauliflower, salmon, tofu, and leafy green vegetables.

According to a panel convened by the National Institutes of Health, women who are still menstruating, or who are postmenopausal but taking menopausal hormone therapy, should consume 1,000 mg of calcium each day. This jumps to 1,200-1,500 mg day for pregnant or breastfeeding women. Postmenopausal women not on hormone therapy should consume 1,500 mg/day.

Recommended daily intake for men is 1,000 mg per day (25-65 years) and 1,500 mg per day from 65 and up. (One glass of skim milk has the same amount of calcium as whole milk -- 300 mg of calcium.)

Because most women take in only half or a third as much calcium as they need through their diet, most doctors recommend calcium supplements to make up the difference. Calcium supplements are available in many forms, but calcium citrate and calcium gluconate appear to be more effective at reducing bone loss. Avoid using dolomite or bone meal as calcium supplements or calcium carbonate supplements labeled "oyster shell," as they may contain lead and other toxic metals.

To help the body absorb calcium, doctors suggest taking vitamin D (400 to 800 IU daily) and magnesium (250 to 350 mg) supplements.

Calcium supplements can inhibit the absorption of certain drugs. Check with your doctor before beginning calcium supplements. You may need to take your supplements at a different time than your other medications.

Other Dietary Ways to Maintain Bone

In addition to eating calcium-rich foods, you should also avoid phosphorus-rich ones, which can promote bone loss. High-phosphorus foods include red meats, soft drinks, and those with phosphate food additives. Indeed, several studies have indicated that vegetarians tend to have denser bones later in life than meat eaters, although other studies have shown no such difference. Excessive amounts of alcohol and caffeine are also thought to reduce the amount of calcium absorbed by the body and should be avoided.

To help keep estrogen levels from dropping sharply after menopause, and thus help prevent osteoporosis, some practitioners advise postmenopausal women to consume more foods containing plant estrogens, especially tofu, soybean milk, and other soy products. However, there is no evidence to prove that these foods help prevent or delay the onset of osteoporosis.

At-Home Remedies

Here are two easy ways of increasing the amount of calcium in your diet:

• Add nonfat dry milk to everyday foods and beverages, including soups, stews, and casseroles. Each teaspoon of dry milk adds about 20 mg of calcium to your diet.
• Add a little vinegar to the water you use to make soup stock from bones. The vinegar will dissolve some of the calcium out of the bones, for a calcium-fortified soup. A pint can contain as much as 1,000 mg of calcium.

Exercise

Not only must you get enough calcium in your diet, you must also exercise to maintain strong bones. Studies have shown that weight-bearing exercises -- those that put stress on bones, such as running, walking, tennis, ballet, stair climbing, aerobics, and weightlifting -- reduce bone loss and help prevent osteoporosis. To benefit from the exercise, you must do it at least three times per week for 30 to 45 minutes. Swimming and bicycle riding, although good cardiovascular exercises, do not appear to prevent osteoporosis because they do not put enough stress on bones.

How can I prevent osteoporosis?

• Eat foods rich in calcium, such as nonfat milk, low-fat yogurt, broccoli, cauliflower, salmon, tofu, sesame seeds, almonds, and leafy green vegetables.
• Eat foods that contain plant estrogens, especially tofu and other soy products.
• Avoid foods that can interfere with your body's absorption of calcium, such as red meats, soft drinks, and excessive amounts of alcohol and caffeine.
• Do weight-bearing exercises for 30 to 45 minutes at least three times a week.
• Do not smoke. Some studies have shown that women who smoke increase their risk of developing osteoporosis by 50%.
• Avoid antacids containing aluminum, as they can prevent calcium absorption by binding with phosphorus in the intestines. Many over-the-counter antacids do not contain aluminum and are a good source of calcium.
• The recommended amount of calcium you should eat ranges from 1,000-1,500 mg, with 1,500 mg suggested for older men and postmenopausal women. Preferably, this should be obtained through diet, but calcium supplements should be used when needed.
• Although estrogen therapy after menopause -- used with progestin for women who have not had a hysterectomy -- can help maintain bone, menopausal hormone therapy is no longer recommended because the risks of breast cancer and heart disease are felt to outweigh the bone benefits.
• There are drugs that can maintain or build bone that are often recommended for people, especially women, at high risk of developing osteoporosis.