Levels of bone mineral loss were far higher in a small group of men who had been recently infected with HIV than is typically seen in HIV-negative men of similar age and demographics, according to a study published in the September 10 issue of AIDS.

Numerous studies have now confirmed that bone mineral loss—called osteopenia when the bone loss is moderate and osteoporosis when it is more severe—is far more common in people with HIV, particularly in HIV-positive men. These studies, however, have varied in their methods and in the specific populations they analyzed. For example, most studies have looked predominantly at HIV-positive men and women who had been infected for many years and have been receiving antiretroviral (ARV) therapy. Conversely, few studies have evaluated rates of bone mineral loss earlier in the course of HIV infection.

These factors have made it difficult to understand what, exactly, is driving the higher rates of osteopenia and osteoporosis among people living with HIV. High viral load, low CD4 count, smoking history, low body mass index and certain ARV drugs have all been associated with bone mineral loss, but no studies have been able to prove conclusively that any one of these factors causes the bone condition.

To shed more light on this subject, Marlous Grijsen, MD, from the University of Amsterdam, and her colleagues conducted bone scans on 33 very recently infected men, only one of whom was taking ARV therapy. Most of the men were white and had high CD4 cell counts. The average age was 38, just over half were smokers, and their body mass index—a calculation drawn from height and weight—was generally on the low side of normal. Thirty-two of the subjects were men who have sex with men (MSM).

Many were so recently infected that they didn’t yet test positive by a Western Blot antibody assay: their infections had to be confirmed by viral load. For those in whom infection could be confirmed by Western Blot, the average length of time since a positive test was 24 days.

Grisjen’s team found that bone mineral loss was far more common among the men in their study than what would be expected in HIV-negative men of a similar age. In fact, 45 percent had osteopenia, and 6 percent had osteoporosis. The three factors associated with lower bone density were older age, low BMI and higher levels of thyroid-stimulation hormone.

The reasons for these unusually high rates of bone mineral loss are unclear. There is some evidence, according to Grisjen and her colleagues, that viral replication might have contributed to bone mineral loss. It could also be that other factors—such as recreational drug use—were to blame. Previous studies have found that methamphetamines, nitrous oxide (poppers) and cigarette smoking contribute to reduced bone density. The authors did not have sufficient data to make these kinds of analyses, however.

“This study shows a high rate of osteopenia and osteoporosis early in the course of HIV infection, before the possible influence of [ARVs],” the authors concluded. “Longitudinal studies are needed to evaluate changes over time. Studies involving HIV-negative controls will be a key in understanding whether these findings relate to the presence of HIV or other risk factors affecting bone health among MSM.”