Q: I have chronic asthma and so I use a steroid inhaler. I also take calcium supplements, exercise regularly, and am generally in good health. Should I worry about getting osteoporosis?
A: Yes it may,but before I get into your specific concern I want to address the general misinformation that all osteoporosis is the same: That it’s an affliction of “little old ladies” (which of course it’s not). There are two types of osteoporosis.
Primary osteoporosis is due to a lack of calcium (especially in childhood and adolescence), poor hormonal production (as evidenced by missed periods in the reproductive years, especially with eating disorders), genetic factors (for instance, did your mom have osteoporosis?), diseases such as hyperthyroidism or overactive thyroid, and absence of estrogen (as in menopause).
Secondary osteoporosis is due to medications or behaviors that cause the bone eating cells to overcome the bone building cells so “in sum” bone is lost. The good news is that if you identify secondary osteoporosis in its early stages of development it can be reversed and you can get your bone mass in better shape for later life.
Before we get into the causes of secondary osteoporosis, we first need to talk a bit about bone density tests and bone mass scores. The T-score compares you to the idealized 30-year-old in your ethnic group who has reached her peak bone density. This is the score that doctors use to tell you if you have low bone density (osteopenia) or have such a low bone density (under –2.5) that you qualify for the diagnosis of osteoporosis. The Z- score compares your bone mineral density to other women who are healthy and age-matched. A Z-score of -1 is associated with a two-fold lifetime risk of a fracture, while a Z-score of -2 is associated with a four-fold risk of a fracture. Although doctors tend to ignore Z-scores, they're perhaps the more important value when determining if you have secondary osteoporosis.
To help you determine if you have active breakdown of bone above and beyond that which is normal, your doctor may order specific laboratory tests. These include: calcium, vitamin D, and parathyroid levels measured in blood tests; a 24 hour urine calcium which will assess whether you are absorbing ingested calcium, and a test for thyroid stimulating hormone (TSH). A low TSH level in an individual who is taking thyroid hormone indicates that the replacement is too much; in the case of thyroid, too much of a “good thing” (or hormone) can lead to bone loss.
Now let’s discuss the lifestyle behaviors and medications that can lead to secondary osteoporosis. Taking steroids, even in very low doses and in the inhaled form, can lead to bone loss. So women taking steroids of any kind for more than six months should get their bone density checked and consider medications that prevent additional bone loss. These medications include bisphosphonates such as Fosamax, Actonel, and Boniva. Talk to your doctor about these drugs and in order not to make a bone loss situation worse be sure to take 1,500 mg of calcium a day in divided doses (your body won’t absorb more than 600 mg at a time) and 1,000 IU of vitamin D.
Other medications that have been associated with bone loss and secondary osteoporosis include: Aromatase inhibitors, used to prevent the recurrence of breast cancer. Studies have shown that these estrogen inhibitors lead to a 2.6 percent bone loss per year. Another hormone called gonadotropin-releasing hormone (which diminishes levels of estrogen by preventing ovulation) can lead to a four to six percent bone loss per year.
Now on to behavior... We all know that smoking, lack of exercise as well as general poor nutrition can lead to bone loss over time. But here is a fact that is often overlooked: Anorexia is a leading cause of early age osteoporosis. This eating disorder affects 4 percent of U.S. college students, and, if not treated, can lead to a decrease of 25 percent in bone mineral density and a seven-fold increase in fracture risk. Anorexics eat and absorb less calcium; the latter is due to an absence of multiple hormones like testosterone, cortisone, and estrogen. Simply replacing the estrogen (by using things such as birth control pills) will not correct for the bone loss. Weight gain over time will.
Finally, early menopause is also likely to cause osteoporosis, as is the removal of the ovaries at a young age or ovarian failure. Lack of estrogen from an early age can cause an 8 to 11 percent bone loss per year. The treatment for this, if possible, is to “replace” the lost estrogen and perhaps accompany this replacement with testosterone. In all of these scenarios it’s also important to be sure to take sufficient calcium and vitamin D.
So there you have most of the reasons for secondary osteoporosis. I thought I would go through the entire scenario before I advised you to get a bone density scan.
Dr. Reichman’s Bottom Line: Know your risk factors for osteoporosis. Even if they seem small at the time, they may have long-term effects. Get your bone density tested and, if necessary, ask your doctor for appropriate medications to safeguard your bone support.
Dr. Judith Reichman, the TODAY show’s medical contributor on women’s health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, “Slow Your Clock Down: The Complete Guide to a Healthy, Younger You,” which is now available in paperback. It is published by William Morrow, a division of .
PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.