Updated July 20, 2006

Boning Up on Bone Health

by Belinda O’Connell, M.S., R.D., C.D.E.

After you get your bone mineral density tested, your physician will compare your results against a “normal” standard. One standard, the T-score, compares your bone mineral density to an average, healthy 30-year-old’s bone density. The other standard, the Z-score, compares your bone mineral density to that of a typical healthy person of your age and body size. Because most people lose bone as they age, the age-matched Z-score is less useful in determining risk.

T-scores and Z-scores are measured as a standard deviation, or how different your measurement is from normal. Bone mineral density values that are one standard deviation or less from normal are considered healthy. T-scores that are more than one standard deviation below normal but less than 2.5 standard deviations below normal indicate osteopenia, or low bone mass. Scores that are more than 2.5 standard deviations below normal indicate osteoporosis.

Prevention and treatment
Although osteoporosis can be treated, it cannot be cured, so the best treatment is to take steps to prevent it from developing in the first place. The best protection against osteoporosis is to build as much bone as possible while you are young. Bones are a bit like a bank savings account. If you “deposit” a lot of bone tissue when you are young, you have more to “withdraw” as you age without hitting critically low levels. For children and younger adults, this means being physically active and getting enough calcium and vitamin D. Research indicates that adequate calcium intakes early in life may reduce incidence of hip fractures by 50% later.

Even if you have passed the time period when bone is built most efficiently (from preadolescence until about 30), there is still a great deal you can do to preserve the bone you have. To avoid osteoporosis, or to slow bone mass loss if you already have osteoporosis, take the following steps to control your risk factors:

• Begin to participate in weight-bearing activities such as walking, dancing, or weight lifting. Ask your health-care team to recommend back-strengthening exercises. Try an activity like tai chi or yoga that improves balance.
• If you smoke, ask your physician to help you find a smoking cessation program or to prescribe a medicine to help you control your desire for cigarettes as you quit.
• If you drink alcohol, keep your regular intake to no more than one to two servings per day.
• Make sure that your diet includes the right amount of nutrients like calcium and vitamin D to keep your bones strong.

There are also several different types of medicines that may help slow bone loss or strengthen bone in those diagnosed with osteoporosis. These include the following:

• Estrogen or estrogen/progestin hormone replacement therapy (commonly called HRT) is used to replace estrogen levels in postmenopausal women. It has been shown to decrease bone loss, increase bone density, and reduce hip and spine fractures. However, it is also associated with increased risk of some types of cancer, and recent research indicates it may increase risk of cardiovascular disease.
• Bisphosphonates, which include alendronate (Fosamax), risedronate (Actonel), and ibandronate sodium (Boniva), decrease bone loss, increase bone density, and decrease the risk of fractures in the spine, hip, and other sites. These drugs are used to treat and prevent osteoporosis in men and women as well as bone loss due to steroid therapy. Bisphosphonates must be taken on an empty stomach, and food must be delayed for 30 to 60 minutes after taking the medicine.
• Calcitonin is a hormone that helps the body regulate calcium and bone metabolism. A synthetic version, sold as Miacalcin, is available as a nasal spray or an injection. It can decrease bone loss, increase bone density of the spine, and lower risk of spinal fractures. It may also help control pain associated with spinal fractures. It is FDA-approved to treat osteoporosis only in postmenopausal women, but it may be prescribed off-label to men as well.
• Parathyroid hormone helps to regulate bone and calcium metabolism. A genetically engineered version of parathyroid hormone is available as an injection, called teriparatide (Forteo). Teriparatide promotes the growth of new bone and can decrease hip and spine fractures. It is approved for use in men and postmenopausal women as a treatment for osteoporosis.
• Selective estrogen receptor modulators (called SERMs) are drugs that mimic some of the positive effects of estrogen without the same risk of negative side effects. One that is approved for treatment of osteoporosis is raloxifene (Evista). It has been shown to increase bone mass and decrease bone breakdown and the incidence of fractures.

Belinda O’Connell is a Diabetes Nutrition Specialist at the International Diabetes Center in Minneapolis, Minnesota, and a freelance health and science writer.

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