FIT FOR DUTY. . .FIT FOR LIFE!

Submitted by: CAPT Maureen Leser

OSTEOPOROSIS

Introduction

In 2004, VADM Richard Carmona, Surgeon General of the U.S. Public Health Service issued a Surgeon General’s Report on bone health and osteoporosis to provide much needed information on bone health1. This report extensively reviews the biology of bone, the importance of bone health, consequences of bone disorders such as osteoporosis, a disorder characterized by porous, weak bones, and also calls for a public health action plan to address bone health.

An estimated 10 million Americans over age 50 have osteoporosis while another 34 million have osteopenia, or low bone mass. Osteopenia typically precedes osteoporosis and is also associated with a risk of fracture2. Each year approximately 1.5 million people suffer an osteoporotic-related fracture, and 20 percent of senior citizens who suffer such a fracture will die within 1 year due to complications. The number of hip fractures in the United States is expected to double or even triple by the year 2020 because of our aging population and previous inadequate public health focus on bone health.

Osteoporosis can be particularly devastating to women. Four out of every 10 white women, age 50 or older, in the United States will experience a hip, spine, or wrist fracture sometime during the remainder of their lives; 13 percent of white men in this country will suffer a similar fate. The Surgeon General’s Report also states that lifetime risk for fractures may be rising among Hispanic women.

Appropriate nutrition and physical activity throughout life can decrease risk of bone disease and fractures. The “Fit for Duty” column will present a series of articles to provide public health professionals with current information on the relationship between osteoporosis and calcium, vitamin D, and physical activity; this first article addresses bone itself.

Bones

Bones are living tissues that change throughout life. Adolescence is a particularly critical period for bone health because the amount of bone mineral gained during this period typically equals the amount lost throughout the remainder of adult life. Bones increase in mass until around age 30, when peak bone mass, that point representing maximum bone strength, is reached. Lower peak bone mass is associated with earlier onset of osteoporosis. Scientists have identified factors that increase the risk of developing osteoporosis, including:

Chronically low calcium intake Lack of vitamin D Insufficient physical activity, in particular weight bearing activity Athletic amenorrhea Anorexia nervosa Being female Family history of bone disease Hyperparathyroidism Low body weight (less than approximately 127 pounds) High levels of serum calcium in otherwise healthy individuals

Measuring Bone Mineral Density

Scientists agree that strong bone at age 30 may slow bone loss that occurs with aging and delay the development of osteoporosis. Bone mineral density tests such as DEXA scans are used to assess bone strength1. DEXA is an enhanced form of x-ray technology that is painless and quick. It sends a beam of low-dose x-rays through bones via two energy streams. One energy peak is absorbed mainly by soft tissue and the other by bone. Bone mineral density is the difference between the total and the amount absorbed by soft tissue. DEXA measurements are most often taken of the lower spine and hips.

The following diagram helps interpret bone mineral density tests3-4. If bone mineral density falls in the green area (-1 or greater) bone strength is considered normal. A bone mineral density between -1 and – 2.5 suggests osteopenia while a bone mineral density less than -2.5 is consistent with osteoporosis.

Several groups, including the National Osteoporosis Foundation, have suggested risk factors to determine the need for a bone mineral density test5. In addition to the aforementioned age, gender, and race factors, others include:

All women age 65 and older and younger, postmenopausal women who have risk factors such as a family history of osteoporosis. Women who stop menstruating before menopause because of conditions such as anorexia or bulimia, or because of excessive physical exercise. A person’s bone structure and body weight should be considered: Small-boned and thin women (under 127 pounds) are at greater risk. Current cigarette smoking, drinking too much alcohol, consuming an inadequate amount of calcium or getting little or no weight-bearing exercise. Use of certain medications to treat chronic medical conditions such as rheumatoid arthritis, endocrine disorders (e.g., under-active thyroid), seizure disorders and gastrointestinal diseases may have side effects that can lead to osteoporosis. Potential medications include: glucocorticoids excessive thyroid hormones anticonvulsants antacids containing aluminum gonadotropin releasing hormones (GnRH) used for treatment of endometriosis methotrexate for cancer treatment cyclosporine A, an immunosuppressive drug heparin cholestyramine, taken to control blood cholesterol levels

For many individuals, these are life-enhancing or life-saving therapies. Never stop or alter your medication regimen(s) on your own. It is always important to discuss use of these medications with your health care provider so that individual risk-benefit assessments can be made.

The next article will discuss the importance of calcium for bone health, addressing recommended dietary intake of calcium, potential use of dietary supplements to enhance calcium intake, and factors associated with absorption and metabolic utilization of calcium.

References:

U.S. Department of Health and Human Services. Bone Health and Osteoporosis: A Report of the Surgeon General. Rockville, MD: Public Health Service, Office of the Surgeon General, 2004. http://www.surgeongeneral.gov/library/bonehealth/content.html. Miller et al. Arch Intern Med. 2004;164:1113-20 Office of Dietary Supplements, National Institutes of Health. Dietary Supplement Fact Sheet: Calcium. 4/2005. National Osteoporosis Foundation. Bone mineral density testing: What the numbers mean. NOF, Bone Health Updates. 2001. http://www.nof.org/osteoporosis/bmdtest.htm. National Osteoporosis Foundation. Physician’s Guide to Prevention and Treatment of Osteoporosis, Washington, DC, 2003.

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