June 25, 2012
Young, HIV-infected men -- particularly those on antiretroviral treatment -- are more likely to experience low bone mass than their HIV-uninfected peers, according to a recent U.S. study.
The study, led by Kathleen Mulligan, Ph.D., of the University of California-San Francisco, found that the average hip bone density for male youths living with HIV was 5 to 8% lower than those not living with HIV. Additionally, average bone density in the spine was 2 to 4% lower for those living with HIV.
The researchers enrolled 252 teens and young men, ages 14 to 25. There were 199 HIV-infected participants and 53 HIV-uninfected controls. In the HIV-infected group, 105 had yet to start treatment, while 94 were on regimens that contained either an NNRTI (non-nucleoside reverse transcriptase inhibitor) or a PI (protease inhibitor). About 88% of the study population identified as either African American or Hispanic.
To measure bone density, the participants underwent whole body scans, which also identified the distribution of fat and lean muscle mass. They also answered questions about their medical history, as well as diet, exercise and other lifestyle routines.
According to a National Institutes of Health press release:
The researchers found that the HIV-positive participants who had not yet begun treatment tended to have less body fat than either their counterparts on medication or the study's HIV-uninfected participants.
Both bone density and the calcium and other mineral content of bones tended to be lowest in participants taking medication for HIV. Youth with HIV who had not begun treatment had higher bone mass levels than HIV positive youth who were on anti-HIV regimens, but lower bone mass levels than youth who did not have HIV. Participants' responses to questions about diet indicated that at least half of them did not consume sufficient calcium or vitamin D. The researchers also found that more than 30% of all the participants smoked. Half said they did not get regular exercise. Smoking and lack of exercise can contribute to weaker bones. The study authors noted that additional studies are needed to follow HIV-positive young men long term to determine whether bone loss during adolescence increases the risk of fractures later in life.
"None of the young men we saw is in immediate risk of fracture," said Dr. Mulligan. "However, our results indicated that it would be a good idea for young men newly diagnosed with HIV to make sure they exercise, get enough calcium and vitamin D, quit smoking and limit alcohol consumption."
In addition, study co-author Bill G. Kapogiannis, M.D., commented on the finding that bone mineral density appeared lower among HIV-infected participants on treatment, even though those individuals had not been taking antiretroviral therapy for a long time. "These findings suggest a short-term impact of HIV therapy on bone at ages when people are still growing and building bone mass," he said in the press release. "This raises concern about the risk of fracture as they age."
The researchers noted, however, that the study was not meant to determine causes of bone loss, and pointed out the possibility that the participants could have had low bone mass levels prior to HIV infection. Risk factors for bone loss included tobacco and alcohol use, as well as low intake of calcium and vitamin D, which all the participants experienced.
The results from this study come around the same time as interesting findings from two other recently published studies on bone health and HIV. The first study, published in AIDS, suggested that, for individuals living with HIV, being on treatment decreased the risk of bone fractures. The second study, published in Hepatology, found that HIV and hepatitis C coinfection increased risk of hip fracture.
Warren Tong is the research editor for TheBody.com and TheBodyPRO.com.
Follow Warren on Twitter: @WarrenAtTheBody.