Bone Strength, Osteoporosis, Medications

Bones in flux

Bones are always in a process of growth and resorption: Old bone is absorbed and removed by special bone cells called osteoclasts, and new bone is rebuilt by another group of bone cells, osteoblasts. Osteoblasts apply a kind of spackle, collagen fortified with calcium and phosphorus, to the walls of the bony cavities in a process called mineralization.

Osteoclasts nibble away or resorb the old, worn spots. It's like having a huge old house that you want to keep in tip-top shape: You're fighting weather and day-to-day abuse, forever scraping and redoing the walls and woodwork. Prior to menopause, particularly before age 35, the rate of resorption is equal to the rate of rebuilding, and the strength of your bones is stable.

What is osteoporosis?

After age 35, and particularly after menopause, bone resorption gradually begins to outstrip bone formation, resulting in a slow loss of bone mass. Over time, usually many years, bone mass reaches the low end of the normal range: osteopenia. If loss of bone mass continues long enough, osteoporosis is the result. Osteoporosis may be moderate, associated with an increased risk of fracture, or it can be severe, associated with actual fractures.

Loss of bone mass is an inherent part of the aging process of men and women, although it tends to affect women more. Our bone mass is less dense than men's to begin with, and we tend to live longer, allowing more time for bone aging. Bone mass is greatest in women's 20s and 30s; it stabilizes between 30 and 40, and over 40 there is slow loss of bone strength. After menopause, there is a five- to seven-year period of accelerated bone loss; then the rate slows and returns to an age-related rate.

The aging process has a greater effect on bone loss than the presence or absence of estrogen. Smoking, prolonged bed rest or inactivity, being underweight, and certain medications can increase bone loss. Weight-bearing exercise increases bone mass. Tamoxifen tends to stabilize bone strength, but for the first year of taking it, pre-menopausal women may experience bone loss; post-menopausal women may have some bone fortification.

Osteoporosis can lead to loss of height and small fractures of the vertebral and wrist bones. You're also more vulnerable to large fractures of the hip. Such fractures can have a significant effect on your quality of life. If an elderly woman fractures a hip, forcing her to stay in bed, she is at significant risk for developing complications from the fracture or from the inactivity.

Fewer than 20% of these older women return to their prior lifestyle. And death can occur in up to 30% of women over 75 who develop a hip fracture, because of complications from extended bed rest—like a pulmonary embolus (a blood clot from the thigh or pelvic area that breaks off and travels to the lung). These types of problems generally occur in women over 75.

Measuring osteoporosis

At one time, treatment for critical bone loss began only after a fracture led to the diagnosis of osteoporosis. Now it is possible to diagnose osteopenia and osteoporosis and predict risk prior to fracture, using single- or dual-energy X-ray absorptiometry (DEXA) tests. This X-ray scan measures the bone density of your lumbar spine, because the spine is usually the first area to experience loss of bone mass. (A DEXA scan is different from a bone scan, which you may have had to check the health of your bones and to make sure there was no evidence of metastasis to the bone.)

You probably don't need a special scan to identify bone loss if you have lost height each year (a sign of significant osteoporosis). But if you have just recently experienced any type of menopause, you may not have lost significant height so far, and good medical practice suggests stepping in before you lose ground.

Preventing osteoporosis is particularly important when you have just experienced premature medical or surgical menopause. If you are trying to figure out what you should do, if anything, get a baseline DEXA scan to see how strong your bones are. If there is some evidence of early bone loss, getting two DEXA scans taken one year apart can tell you the rate at which you are losing bone mass.

If you learn that the rate of your bone loss is minimal, you may decide to do nothing besides lifestyle changes. It's still important to keep your bones strong and to periodically reassess how your bones are doing. If, on the other hand, you find that your rate of bone loss is significant, you may be motivated to do more to actively prevent osteoporosis.

For more information about the DEXA scan technique and the location of a scanner near you, as well as general information on osteoporosis and the various medications used to treat it, call the National Osteoporosis Foundation's general information line, at 800-464-6700. The cost for a DEXA scan is $125–$350.

Keep your bones strong

The most effective way to maintain the strength of your bones requires a combination of lifestyle changes and medical measures.

Lifestyle changes:

• Stop smoking.
• Do weight-bearing exercise, ideally thirty minutes a day, three or more days a week.
• Practice good nutrition, including minimal amounts of animal protein and sufficient calcium intake.
• Prevent falls, since most fractures are preceded by falls.

Medical measures:

• Calcium supplements are recommended to most women: 1000–1500 milligrams per day (but check with your doctor first to be sure your calcium level is not too high to begin with).
• Vitamin D supplements (not to exceed 400 I.U. daily) may be recommended if dietary intake is inadequate.
• Fosamax (alendronate sodium), Miacalcin (nasal calcitonin), or Slow Fluoride (a slow-release sodium fluoride) taken in combination with Citracal (calcium citrate), and SERMs such as tamoxifen (Nolvadex) or raloxifene (Evista), represent a range of pharmaceutical choices if you have osteoporosis. Consult your doctor about these options.

Promising new medications

Fosamax: Fosamax is one of a new class of medications called bisphosphonates that halt the rapid bone loss you may experience beyond menopause. It may even help restore some of the bone mass you have already lost. With a dose of 10 milligrams daily, Fosamax stabilizes bone mass and reduces the number and severity of bone fractures. It is not a hormone and it has no apparent effect on breast cancer. In one study comparing Fosamax to MHT, they were equally effective in halting bone loss. There is evidence that Fosamax can actually increase bone density, not just restore an equal balance of bone resorption and formation.

Fosamax requires your doctor's prescription. It can affect your kidneys if they are not functioning well, or worsen an existing problem with your esophagus. Side effects include irritation of the esophagus; gastrointestinal symptoms such as nausea, constipation, heartburn, and diarrhea; and muscle or bone discomfort—all usually mild and transient.

The biggest problems with the drug—apart from cost—are that you cannot lie down for at least thirty minutes after you have taken it, to avoid irritation of the esophagus, and that the drug is absorbed well only if taken on an empty stomach. (And then you have to wait at least thirty minutes before you can eat or take other medications.)

SERMs: Important improvements in the management of osteopenia and osteoporosis will come from SERM medications. Raloxifene (brand name: Evista) is the first SERM to be approved for the treatment of osteoporosis. In women with osteoporosis (not women with or at high risk for breast cancer), study results also show it can reduce risk of breast cancer and lower cholesterol, without stimulating estrogen receptors in the endometrium (uterine lining).

Raloxifene can produce hot flashes and vaginal dryness or discharge in some women. It's not perfect, but it is a big step forward. Tamoxifen (Nolvadex) is also effective at keeping bones strong and reducing the risk of breaking a bone after menopause.

If you have experienced a significant loss of bone density, you can use both Fosamax and raloxifene. Or if you are already on tamoxifen, stay on it, and add Fosamax. When bone density approaches normal levels, you can then discontinue Fosamax and continue with raloxifene to maintain bone density (and possibly help gain protection against cancer).

Other hormonal therapies: The hormone calcitonin also reduces the rate of bone resorption, but it is probably not as effective as Fosamax. It comes in two forms, Calcimar and Miacalcin. Slow Fluoride taken with Citracal stimulates bone formation, increasing bone density and preventing new spinal fractures.

Estrogen prevents further bone loss by inhibiting bone resorption, and over time it helps reduce compression fractures of the spine, wrist, and hip. It does not appear to help rebuild bone or increase bone mass. If you have had breast cancer and cannot take MHT, these other therapies are effective alternatives. Each of these treatments costs about $50 a month.

If you have osteoporosis

Aggressive medical management is called for if you have osteoporosis or progressive bone loss with a significant spinal deformity, such as kyphosis (prominent back hump) or scoliosis (side-to-side curvature of the spine) or other severe postural problems. Adopting lifestyle changes—and sticking to them—is essential for you. You and your doctor should consider some of the medications discussed above to prevent further loss of bone integrity. For women who have had breast cancer, MHT should be avoided, until proven safe and more effective than alternatives.