Studies have documented that osteopenia and osteoporosis are more common among HIV-positive patients, compared to HIV-negative individuals of the same sex and age. However, the reasons for this are not clear.
Is HIV infection itself to blame? Possibly. A number of potential connections between HIV and bone loss are being studied. For example, HIV infection can increase certain proteins in the body – including interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-a) – that may also be responsible for accelerated bone loss. It's also possible that the constant level of T-cell activation in the body may have an effect on bones. Some researchers have also speculated that HIV's ability to infect cells in the bone marrow may be to blame.
It's also possible that the medications used to treat HIV may have a negative effect on bone health. There have been studies linking protease inhibitors (PIs) and nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) to decreased BMD in HIV-positive people. Some research suggests that protease inhibitors can impair the way the body utilizes vitamin D, which is essential to bone health. There has also been research suggesting that the mitochondrial toxicity caused by some NRTIs can impair the function of osteoblasts. Additionally, there has been research linking body-shape changes (lipodystrophy) – which can be caused by PIs and NRTIs – to decreased bone density. A majority of studies now find that the use of ARV medications typically results in a 2 to 6 percent bone loss within the first two years after starting treatment—about the same as that seen in women after the onset of menopause. Fortunately, longer-term use of ARVs does not appear to cause chronic and progressive bone loss beyond the first two years of treatment.
One thing is certain: the risk of osteopenia/osteoporosis increases with the length of time someone has been infected with HIV. Moreover, HIV-positive people who have other risk factors for osteopenia/osteoporosis, such as those listed in "What are the risk factors for osteoporosis?" may be at an increased risk for these bone problems.
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