The Effect of Vitamin D and Calcium on Bone in Pediatric HIV

We have observed that vitamin D deficiency, as evidenced by low serum 25(OH)D concentrations, is common in children and adolescents with HIV infection. To determine whether vitamin D and calcium supplementation improve bone mineral content (BMC) and bone mineral density (BMD) in HIV-infected children and adolescents, we propose a double-blind, randomized, placebo-controlled trial comparing supplementation with oral vitamin D and calcium to placebo. The specific aims of this project are to: 1. Determine the effect of vitamin D and calcium supplementation on bone mineral accrual in HIV-infected children. We hypothesize that BMC and BMD will increase to a greater extent in HIV-infected children who receive supplementation with vitamin D and calcium. This hypothesis will be tested by comparing changes in BMC and BMD, measured by dual energy x-ray absorptiometry (DXA), after one and two years of treatment in HIV-infected children and adolescents receiving vitamin D and calcium supplementation compared to those receiving placebo. 2. Determine the effect of HIV infection and vitamin D and calcium supplementation on indices of mineral metabolism and markers of bone turnover. We hypothesize that indices of mineral metabolism and markers of bone formation and resorption will return toward normal in HIV-infected children and adolescents who are randomized to receive vitamin D and calcium supplementation. We will test these hypotheses by comparing longitudinal changes in indices of mineral metabolism and bone turnover markers in HIV-infected children and adolescents receiving vitamin D and calcium supplement versus those receiving placebo 3. Evaluate if vitamin D stores are a determinant of bone mass in HIV infected children and adolescents receiving HAART. We hypothesize that vitamin D stores, as assessed by serum 25-hydroxyvitamin D levels, are an important determinant of bone mass in HIV-infected children and adolescents receiving HAART. We will test this hypothes