Osteoporosis : Diagnosis, Treatment Options

by Food and Drug Administration (FDA)

(Page 2 of 3)

Diagnosis

Because the changes at menopause increase a woman's risk, many physicians feel it's a good time to measure a woman's bone mineral density, especially if she has other risk factors for osteoporosis.

"The best way to gauge a woman's risk for osteoporotic fracture is to measure her bone mass," says Insogna.

Routine X-rays can't detect osteoporosis until it's quite advanced, but other radiological methods can. The FDA has approved several kinds of devices that use various methods to estimate bone density. Most require far less radiation than a chest X-ray. Doctors consider a patient's medical history and risk factors in deciding who should have a bone density test. The method used is often determined by the equipment available locally. Readings are compared to an internationally accepted standard based on young Caucasian women. Different parts of the skeleton may be measured, and low density at any site is worrisome.

Bone density tests are useful for confirming a diagnosis of osteoporosis if a person has already had a suspicious fracture, or for detecting low bone density so that preventive steps can be taken.

"There's a profound relationship between bone mass and risk of fracture," says Robert Recker, M.D., director of the Osteoporosis Research Center at Creighton University in Omaha, Neb.

Readings repeated at intervals of a year or more can determine the rate of bone loss and help monitor treatment effectiveness. However, estimates are not necessarily comparable between machine types because they use different measurement methods, cautions Joseph Arnaudo, in the FDA's Center for Devices and Radiological Health. "You always want to go back to the same machine, if you can," he says.

A newer technique for evaluating bone strength is ultrasound, and the FDA has approved several instruments for this purpose. "These machines use the same principles that are employed when using ultrasound to look at fetuses during pregnancy," says Leo Lutwak, M.D., Ph.D., of the FDA's Division of Reproductive, Abdominal, and Radiological Devices. "Although this measurement examines different properties of bone than do X-ray-based bone densitometers, the results are also useful for prediction of fracture." The devices for ultrasound measurement are cheaper and easier to use. This makes them available in more locations and allows evaluation for osteoporosis in many more subjects. "Because they don't use X-rays, they are safer and may be used for repeated examinations, even in pregnant women and children, so they provide a means for better public health practice," Lutwak says.

Another new test provides an indicator of bone breakdown. In 1995, the FDA approved a simple, noninvasive biochemical test that detects in a urine sample a specific component of bone breakdown, called NTx. Clinical labs can get results in about 2 hours. The NTx test, marketed as Osteomark, can help physicians monitor treatment and identify fast losers of bone for more aggressive treatment, but the test doesn't measure bone metabolism specifically, so it may not be used to diagnose osteoporosis.

Expanding Treatment Options

Physicians and patients now have more treatment options. Under FDA guidelines, drugs to treat osteoporosis must be shown to preserve or increase bone mass and maintain bone quality in order to reduce the risk of fractures.

An important treatment option became available to women in November 2002. Forteo (teriparatide) is the first treatment that stimulates new bone growth to increase bone mass. Forteo is a portion of human parathyroid hormone, which works in the body to regulate the metabolism of calcium and phosphate in bones. The treatment is given in daily injections and is approved for postmenopausal women who are at high risk for bone fractures.

The approval of this treatment comes with a strong caution from the FDA: In the pre-approval studies of Forteo using rats, there was an increase in the incidence of osteosarcoma, a rare but serious cancer of the bone. Because it's possible that women treated with Forteo could have increased risk for developing this cancer, doctors are advised to discuss this risk with their patients and be sure that it's the best treatment. Women who are prescribed Forteo receive an FDA-approved medication guide that explains the benefits and risks and gives other advice about how to use the treatment properly.

All other drugs approved for osteoporosis treatment act by slowing the turnover of bone, rather than stimulating new bone formation. Increases in bone mass are most pronounced in the first year or two after treatment with the drugs begins, then taper off. Any gain is helpful, even if it doesn't continue, because increases in bone mass help reduce fracture risk.

In the mid-1990s, the FDA approved the first nonhormonal treatment for osteoporosis. Alendronate, marketed as Fosamax, falls within a class of drugs called bisphosphonates. In clinical trials, Fosamax increased the bone mass as much as 8 percent and reduced fractures as much as 30 percent to 40 percent, depending on skeletal site.

To avoid damage to the esophagus, Fosamax should be taken according to the instructions. These instructions include taking the drug in the morning upon awaking and at least half an hour before eating. The drug should be taken with a glass of water, and the person should remain upright for half an hour after taking it. Fosamax should not be taken by people who cannot stand or sit upright or who have disorders that prevent esophageal emptying into the stomach.

Other drugs recently approved for the prevention and treatment of osteoporosis are Actonel (risedronate), a bisphosphonate similar to Fosamax, and Evista (raloxifene), a drug in a class known as selective estrogen receptor modulators, or SERMs. Both drugs have been shown to reduce the risk for fracture of the spine. Calcitonin is a hormone that plays a role in calcium and bone metabolism. When used regularly, it can slow the loss of bone. Available for many years as an injection, calcitonin treatment became much easier when FDA approved a nasal spray.

Fluoride, known for fighting dental cavities, stimulates bone building, but studies in osteoporosis patients have found that the structure of the new bone was abnormal and weaker than normal bone.

While estrogen may be a good option for some women, new guidelines developed in 2003 by the FDA advise doctors to consider alternative treatments. These changes were prompted by studies indicating that women who take estrogen or estrogen with progestin products after menopause are at higher risk for other conditions, including cardiovascular disease and breast cancer. Because of this, estrogen-containing products should only be considered for women at significant risk of osteoporosis.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.