Vitamin D3 Beneficial for HIV-Infected Youth Receiving Tenofovir

Brian Hoyle

March 03, 2011

March 3, 2011 (Boston, Massachusetts) — The results of a randomized double-blind placebo-controlled study have shown that a 12-week course of high-dose vitamin D3 supplementation is safe and significantly reduces both vitamin D insufficiency and serum parathyroid hormone (PTH) levels in HIV-positive youth who are being treated with the reverse transcriptase antiretroviral tenofovir.

The results were reported here at the 18th Conference on Retroviruses and Opportunistic Infections.

The investigators said that although the length of the study precludes conclusions about clinical significance, the results provide clear evidence of the value of vitamin D supplementation in young tenofovir-treated HIV-infected patients.

"By giving vitamin D once a month in a short 3-month study, we showed that, in HIV-infected patients taking tenofovir, the levels of PTH came down — not to the low levels you would see in people not on tenofovir — but we were able to decrease the level of PTH by 46% in patients taking tenofovir. In patients not taking tenofovir, vitamin D supplementation had no effect," principal investigator Peter Havens, MD, program director, HIV, at the Children's Hospital of Wisconsin in Milwaukee, told Medscape Medical News.

Tenofovir has been linked to increased bone loss, as evidenced by elevated levels of PTH and reduced renal tubular phosphate absorption. This reduced absorption is a hallmark of vitamin D deficiency (a serum level of 25-OH-vitamin D3 below 30 ng/mL), and can be at least partially reversed by vitamin D supplementation. Vitamin D deficiency occurs in more than 80% of HIV-positive youth in the United States.

"You have a high PTH level with vitamin D deficiency in people taking tenofovir. So, we asked ourselves, would treatment with vitamin D, which brings down the PTH level in vitamin D-deficient patients, bring down the PTH level in HIV-positive patients who were taking tenofovir, since, in some ways, tenofovir use looks like vitamin D deficiency from the perspective of having an elevation in PTH," Dr. Havens told Medscape Medical News.

Of the 203 participants 18 to 24 years of age (median age, 23 years), 118 were receiving antiretroviral therapy plus tenofovir and 85 were receiving antiretroviral therapy alone.

Within the 2 groups, participants were randomized to receive vitamin D3 (n = 102) or placebo (n = 101). Vitamin D3 was given once every 4 weeks for 12 weeks as a 50,000 IU dose (an average daily dose of 1700 IU, more than double the Institute of Medicine recommended daily dose of 600 IU). The dose schedule was deliberately designed to be adolescent-friendly, given the notorious problems with daily compliance in this age group, Dr. Havens said.

Both groups were similar at baseline in a number of germane characteristics, including race/ethnicity, body mass index, vitamin D3 level, and self-reported calcium intake.

At baseline, 17% of patients had vitamin D levels that met the standards of clinical sufficiency. At week 12, 52% of those receiving supplementation met the standards of clinical sufficiency. In patients receiving placebo, 16% had sufficient levels of vitamin D at both baseline and week 12.

"This is the first randomized trial of vitamin D replacement in HIV-infected patients. I think that one thing that clinicians have wondered is whether a vitamin D replacement would be effective in people with HIV. This study shows that replacement is effective," said Judith Currier, MD, professor of medicine at the University of California at Los Angeles, told Medscape Medical News.

The results are the first step toward longer-term trials that will study the effect of supplementation with vitamin D and calcium, as well as the effect of various doses of vitamin D. The goal is to optimize the dose, Dr. Havens said.

"That's where we are heading. For now, this preliminary end point of reduced PTH is very reassuring," he told Medscape Medical News.

"I think it's an interesting study that moves the field some, particularly in our understanding of the effect of vitamin D on PTH in tenofovir-treated patients. The randomized trial design is a big strength; this really is the only way to sort out the effects of vitamin D. I hope the authors' next study will include a more clinically relevant outcome like bone mineral density," Todd Brown, MD, PhD, assistant professor of medicine and associate director of the HIV lipodystrophy clinic at Johns Hopkins Medicine, Johns Hopkins University, in Baltimore, Maryland, told Medscape Medical News.

Dr. Havens reports financial relationships with Abbott Labs, Bristol-Myers Squibb, Gilead Science, Janssen, Merck Sharp & Dohme, Tibotec, and ViiV Healthcare. Dr. Brown reports financial relationships with Abbott Labs, Bristol-Myers Squibb, EMD-Serono, Gilead Science, GlaxoSmithKline, Merck, Theratechnologies, and ViiV Healthcare.

18th Conference on Retroviruses and Opportunistic Infections (CROI): Abstract 80: Presented March 1, 2011.

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