Osteoporosis - Hormone Therapy And Disease: Menopause Managing The Change Of Life

Figure 5: The bone-building process

Bone is constantly being built and broken down by the body. Cells known as osteoclasts break down bone, releasing calcium into the bloodstream (A). The trenches left behind (B) are filled in by osteoblasts (C), which mix with calcium and other minerals to form a cement-like substance that completes the bone-building process (D).

Bone mineral density testing — the numbers game

By the time the average American woman reaches menopause, her bone mass has been dwindling for 15 years or more. The most effective method physicians have to determine how strong a woman's bones are is bone mineral density (BMD) testing. (See Table 7 for recommendations about who should get bone density tests.)

Several methods can be used to measure BMD, but physicians consider dual-energy x-ray absorptiometry (DXA) to be the gold standard. DXA is similar to traditional x-rays, but it is more accurate and uses only a fraction of the radiation produced in a standard chest x-ray. DXA usually measures bone mineralization at the hip and spine, two sites that are susceptible to fractures as women get older. Women who undergo DXA more than once should try to have their tests on the same equipment each time. The machines are individually calibrated, and results may vary from one to another.

There are two ways to interpret the results of bone mineral density measurements — with Z-scores or T-scores. The Z-score compares a woman's bone density with that of healthy women of the same age. The T-score compares a woman's bone density with that of a young, normal woman at peak bone mass.

The World Health Organization (WHO) uses T-score results to define a diagnosis of osteoporosis. The diagnosis is based on standard deviations, a scientific way of measuring change. One standard deviation is equal to about a 12% change in BMD. According to WHO, a score above -1 is normal because it is within one standard deviation of zero, the comparison point. Scores between -1 and -2.5 qualify for a diagnosis of osteopenia, or low bone mass. A score below -2.5, or more than two and half standard deviations below the norm, merits the diagnosis of osteoporosis.

The scores have to be put in context, however. A woman's age, her risk factors for osteoporosis, and her general health also should be considered. For example, a woman in her 40s who has a score of -2.5 should be more concerned than an older woman with the same score because she has more time to lose additional bone mass. On the other hand, the younger woman is less likely to have a bone fracture because she is stronger, has better balance, and is less likely to fall. WHO is currently working on a way of reporting bone densities that includes a fracture risk assessment as well as the number reflecting how dense the bone is.

Women diagnosed with osteopenia should recognize that their scores don't mean they have a disease. They've experienced thinning of bones, which happens to all women as they age. There probably is no reason to give up a favorite sport, such as skiing, just to protect against fractures. Instead, women should consider osteopenia a sign that it's time to adopt bone-healthy habits to prevent osteoporosis from developing, such as taking calcium supplements and vitamin D and getting plenty of exercise. You can also talk with your doctor about medications that prevent osteoporosis.

Table 3: Non-estrogen medications approved for osteoporosis

Medication

Brand name

Approved uses

Benefits

Comments

Alendronate

Fosamax (daily or weekly pill or liquid)

Prevention and treatment in postmenopausal women. For men and women with glucocorticoid-induced osteoporosis.

Increases bone density at spine and hip. Reduces the risk for spine and hip fractures. Side effects uncommon.

Difficult to digest. May cause nausea, heartburn, or irritation of the esophagus if not taken properly.

Risedronate

Actonel (daily or weekly pill)

Prevention and treatment in postmenopausal women. For men and women with glucocorticoid-induced osteoporosis.

Increases bone density at spine and hip. Reduces the risk for spine and hip fractures. Side effects uncommon.

Difficult to digest. May cause nausea, heartburn, or irritation of the esophagus if not taken properly.

Ibandronate

Boniva (once-a-month pill)

Prevention and treatment in postmenopausal women.

Increases bone mass. Reduces vertebral fractures.

Difficult to digest. May cause ulcers, nausea, heartburn, or irritation of the esophagus if not taken properly.

Raloxifene

Evista (daily pill)

Prevention and treatment in postmenopausal women.

Increases bone density, although not as much as the bisphosphonates. Reduces the risk for spinal fractures. May reduce breast cancer risk. Lowers LDL (bad) cholesterol.

Side effects are uncommon, but can include hot flashes, leg cramps, and blood clots.

Calcitonin

Miacalcin; Calcimar (daily pill or injection)

Treatment only; not for prevention.

Increases bone density but not as dramatically as any of the other approved medications. Reduces the risk for spinal fractures and possibly osteoporosis-related back pain.

The injected form can cause flushing of the face and hands, nausea, increased urination, and rash. The nasal spray can cause a runny nose.

Teriparatide (parathyroid hormone, or PTH)

Forteo (daily injection)

Treatment only in men and postmenopausal women.

May double the rate of bone formation. Reduces vertebral and nonvertebral fractures.

Must be taken as an injection. Because effects appear to wane and long-term safety data are lacking, PTH should not be prescribed for more than two years. Expensive.