Brittle-bone disease, or osteoporosis, is often not diagnosed until a fracture occurs. Osteoporosis is defined by low bone mineral density (BMD) on an X-ray bone-density scan. If a scan shows your bone density is a bit low, your diagnosis is osteopenia, or pre-osteoporosis. If your BMD is quite low, the diagnosis is osteoporosis. (The results of bone-density scans are expressed in terms of T scores. Scores ranging from -1.0 to -2.5 indicate osteopenia; less than –2.5 means osteoporosis.)
Regardless of the cause, if you have low bone density you’re facing a higher-than-average risk of breaking a bone. If you are lucky, your doctor will recognize some of the risk factors and send you for a bone density scan before you have to endure the pain and recovery of a broken bone.
Some risk factors of osteoporosis are avoidable, while others aren’t. While you can’t do much to alter your family history or certain medical conditions (such as Cushing’s disease and hypothyroidism), you can most certainly address certain bad habits, like smoking and drinking to excess, as well as be proactive about your nutrition and exercise. In this section, you’ll learn some of the preventive steps you can take to ensure healthy, strong bones.
WHAT AFFECTS OSTEOPOROSIS?
Children are taught that bones are like steel girders, the framework of the glorious structure that is the human body. The problem with that analogy is that girders are designed to last hundreds of years without losing strength. In reality, bones are more like the interstate highway system — they fall apart, crack, get potholes, and then get patched up again so we can continue using them.
In addition, unlike steel girders, our bones consist of different layers, with varying density. The outer layer is called compact bone, and it is relatively solid. But just under the compact bone is another layer called spongy bone, which isn’t soft, but it is porous, with holes like a sponge or Swiss cheese. And because bone is live tissue, there are also nerves and blood vessels to feed the cells, as well as other structures.
Bones also contain specialized cells that help form bone (osteoblasts) and break down or resorb bone (osteoclasts). Osteoclasts and osteoblasts work like little construction crews, constantly remodeling, working to keep the bones healthy and strong. If your overall health is good and you eat nutritionally sound meals, a balance is maintained — for every bit of bone lost, an equal amount of bone is created.
With osteoporosis, though, more bone is lost than formed. As you might imagine, the spongy bone — with all its holes and slender walls — becomes weak and compromised more quickly than compact bone. Breaks can occur anywhere, but the most common sites are the hip and wrist, which are more likely to bear the impact of a fall. The bones of the back (vertebrae) are also affected, but they don’t break; they are crushed. The weight of the body is enough to compress the back bones, causing a multitude of tiny fractures in the spongy bone. Over time people with osteoporosis can become shorter — they lose a little height each time a vertebra compresses.
No one knows definitively what causes some people to develop osteoporosis, but some risk factors are clear:
Estrogen and testosterone are important for bone health because they regulate bone loss, or resorption. Both these hormones seem to inhibit the formation of osteoclasts (the cells that break down bone), so when hormone levels are high, there are more bone-building cells than bone-destroying cells. If hormone levels fall, the balance shifts, and bone density is lost.
The question, then, is what causes levels of estrogen or testosterone to fall? The most common cause is aging. Men can develop osteoporosis when they get older as testosterone levels slowly decline. For women, menopause causes an extreme drop in estrogen, and their greatest bone loss occurs within the first ten years after menopause. That’s why many physicians recommend that women get a bone-density scan when they turn 50 or when they enter menopause, whichever comes first. That first test acts as a baseline. The scan should be repeated one or two years later to get a sense of the rate of bone loss.
Menopause isn’t the only condition that triggers osteoporosis. Unfortunately, I’ve been seeing a lot of young women in my practice, women referred to me by their doctors because eating disorders have begun to ravage their bones. When a woman’s weight drops too low, her hormones get out of whack, her estrogen levels fall, and she stops menstruating.
In terms of bone health, a too-thin woman in her 20s looks a lot like a post-menopausal woman in her 60s. The only real cure is for the young woman to gain enough weight to start menstruating again, and then to maximize her bone density while she can — that is, until about age 30, when bone density reaches its peak.
Corticosteroid medications are used to treat a number of common illnesses, including asthma and some autoimmune disorders. But steroids seem to inhibit the bone-building activity and may also increase bone resorption. It has been estimated that up to half of all people who take steroids long-term will end up with osteoporosis. Significant bone loss can occur after even a relatively short course of corticosteroids — 7.5 mg of prednisone for two to three months may require treatment to prevent bone loss.
Bones get stronger if they get more use. In the earlier stages of life, exercise helps build bone. And as much as it pains me to say it, weight builds bone. When it comes to osteoporosis, thin women have a greater risk than heavy women. Think about it — bones that support a 170-pound woman work harder than bones that carry a 110-pound woman.
Studies have shown that lean muscle mass helps strengthen bone density more than fat, but overall weight still contributes to strong bones. Of course, my advice is not for you to put on a few pounds for the sake of strengthening your bones! Being overweight puts you at greater risk for so many life-threatening diseases that it is never a wise choice. But women who diet excessively to keep their weight fashionably low are hurting their bones, now and in the future. If you have a low body weight, you’ll want to be especially diligent about performing strength training exercises to build up your lean mass and give your bones a workout.
Any disorder that reduces the body’s ability to absorb calcium and other nutrients can cause osteoporosis. The most common is celiac disease, an autoimmune disorder that causes the small intestines to lose their absorption capability. Previously thought to be a rare disease of childhood, celiac disease is now known to affect about 1 percent of Americans and can strike at any age.
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