Tenofovir (found in Viread, Truvada and Atripla) is associated with an increased risk for kidney tube dysfunction in people with HIV, notably as they age, according to a study published in the March 27 issue of AIDS. People with damaged kidney tubes can ultimately have problems not only with their kidneys, but also with bone mineral absorption.

Because tenofovir is chemically similar to other drugs known to cause kidney toxicity, researchers have carefully searched for signs of kidney trouble in people taking the drug. Some people on tenofovir have developed severe kidney problems, but these cases are very rare. Dysfunction of the tubes within the kidney—responsible for transporting chemicals from the blood to urine—has also been a concern with tenofovir and has been documented in various studies.

To further explore whether tenofovir is associated with tubular dysfunction, Pablo Labarga, MD, PhD, from the Infectious Disease Department at the Hospital Carlos III in Madrid, and his colleagues conducted blood tests of 283 people living with HIV. Of those patients, 153 were on antiretroviral (ARV) therapy that included tenofovir, 49 were on ARV therapy and had no history of tenofovir use, and 81 had never taken ARVs. The patients were similar in most factors that are associated with kidney function, except that those not on ARVs were younger and people taking tenofovir had a higher body weight than the rest and were more likely to be infected with hepatitis C virus (HCV) or hepatitis B virus (HBV).

Labarga’s team found that 22 percent of those on tenofovir had tubular dysfunction, as did 6 percent of those taking ARV drugs without tenofovir and 12 percent of those with no history of ARV use. After accounting for all other factors, the risks that remained significant predictors of tubular dysfunction were tenofovir and older age.

Though the authors did not find that tubular dysfunction was associated with other kidney toxicity, they are urging health care providers to closely monitor kidney function and bone mineral levels in people taking tenofovir. This is because more people with HIV are entering their 50s and 60s and because tubular dysfunction may further increase the risk of low bone mineral density—osteopenia and osteoporosis—over longer periods of time.