Boning Up on Bone Health
Growing Evidence Suggests That People With HIV May Be at Risk of Bone-Related Problems
The results of David Vereschagin's first-ever bone scan, performed in 2009, threw him for a loop. At age 52, he was told that he had the spine of a 70-year-old. He was cautioned against activities that might strain the bones of his spine because they could fracture.
This unsettling news was all the more surprising because Vereschagin had experienced very few health problems since testing HIV positive in 1995. In fact, for 10 years after his diagnosis he remained healthy without anti-HIV medications, beginning treatment only in 2005, when his CD4 count fell below 300 -- had he waited until his count fell below 200, he would have been at risk of life-threatening complications. Since starting treatment, his CD4 count had risen and until that bone scan his only other setback had been a bout of kidney stones, a problem that was mostly under control.
Unfortunately, the caution against "spine-straining" activities included the gym workouts he had come to love. The warning "really put a fear of weight training into me," Vereschagin recalls, "like one day I was going to lift too much and suddenly hear my spine snap." His workouts were a significant part of his healthy living routine and Vereschagin couldn't give them up: "I just did it with a lot more anxiety."
In the meantime, his HIV specialist muddied the waters with a surprising opinion: She "wouldn't have bothered" with the scan, because "nobody knows what to do" with the information scans provide. Vereschagin recalls feeling caught in the middle of these conflicting points of view and "hopelessly muddled" by this extra twist.
What exactly is going on with people with HIV/AIDS (PHAs) and their bones? Is it possible to find some answers without anxiety and confusion? Let's give it a shot.
Hold on to Your Bones
Bones are strong, but they aren't solid -- their texture is dense in some spots but spongy in others. Bone mineral density (BMD) is the measurement that doctors use to evaluate the density, and by extension the sturdiness, of a bone. Bone density can vary between bones (for example, Vereschagin was told he had low spine BMD but that his hips were fine) and it changes over time. That's because bones are living parts of your body, constantly being worn away and rebuilt. From our mid- to late-20s (when bones are at their strongest) into old age, bones erode slightly faster than they are replaced, gradually weakening the skeletal structure.
In other words, losing bone density is a normal part of aging and is not a problem when the degree of loss is small. Healthy bones are so sturdy that we can afford to lose quite a bit of bone density without any serious risk of breaking them. Loss of a moderate amount of BMD is called osteopenia. If the loss continues, bones become porous, fragile and prone to breaking -- a more serious condition known as osteoporosis. Neither condition typically causes any noticeable symptoms, so they can easily go undetected until a bone breaks.
Dr. Jason Szabo, assistant professor of family medicine at McGill University, suggests that the best way to think of bone density is "as a bank account. You build it up when you're young, with good nutrition and exercise. Then beyond a certain age, you're making small withdrawals each day. If you haven't built up a good 'balance' earlier, you're more at risk of becoming overdrawn -- that is, getting osteoporosis."
Traditionally, in people without HIV, bone problems are most common in postmenopausal women because hormonal changes lead to a significant decline in BMD. But men with HIV are developing bone problems at an unusually early age, and postmenopausal women with HIV are more likely to develop osteoporosis and osteopenia than their HIV-negative counterparts. Figures vary, but studies suggest that osteoporosis may affect about one in 10 PHAs. And many studies have found that osteopenia (less severe bone loss) affects 30 percent or more of PHAs.
A Bone of Contention
The next question is: Does osteoporosis translate into an increased risk of breaking bones for PHAs? That's certainly the case in postmenopausal women with osteoporosis, with or without HIV, so it might seem a foregone conclusion for PHAs as well. But some experts (like Vereschagin's specialist) argue that the studies we have so far are not conclusive and that we need to do more research before we can say for sure.
Dr. Szabo is less optimistic. "We know, because of several large observational studies, that HIV greatly increases the risk of osteoporosis. Prospective studies -- the kind that tell us about the outcomes [of a disease or treatment] -- are much more limited. But some data do suggest that osteoporosis in people with HIV is a risk factor for fractures. I suspect that as years go on, we'll see greater numbers of osteoporotic fractures in our HIV-positive patients."
One study found that HIV, independent of other risk factors, increased the risk of broken bones in men by about 40 percent. While this does not appear to be the case in younger HIV-positive women, more research on older women with HIV is needed to say whether they are at higher risk of breaking a bone due to their HIV status.
What's Behind the Bone Loss?
What causes one person to develop bone disease and another to maintain strong healthy bones into old age? Traditional risk factors for osteoporosis include:
People with HIV have additional risk factors for osteoporosis, including HIV infection itself: the degree of BMD loss has been shown to increase with the duration of infection. But evidence also suggests that some anti-HIV drugs, such as protease inhibitors, may be a risk factor for osteoporosis. Some studies have also suggested that the anti-HIV drug tenofovir (Viread, also in Truvada and Atripla) might have an impact on bone density, but this is not so simple. Studies found that in the year after starting the nuke, people showed rapid loss of bone density, but after this initial decline, the rate of bone loss stabilized. The take-home message: If you are taking protease inhibitors or tenofovir, you probably shouldn't switch away from them purely because of concerns about bone loss. If you are on tenofovir and see a significant loss of BMD, you should talk to your doctor about getting tested for phosphate wasting, as tenofovir use can lead to low levels of phosphate, a mineral needed to keep your bones healthy.
This article was provided by Canadian AIDS Treatment Information Exchange. It is a part of the publication The Positive Side. Visit CATIE's Web site to find out more about their activities, publications and services.
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