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Monthly Vitamin D May Improve Bone Density in People With HIV
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20th International AIDS Conference, July 20-25, 2014, Melbourne
Mark Mascolini
Monthly vitamin D supplementation with calcidiol (25-hydroxyvitamin D, 25-OH-D) appeared to improve bone mineral density (BMD) in a nonrandomized prospective study of HIV-positive adults in Spain [1]. Researchers from Madrid's Ramon y Cajal Hospital believe BMD gains in people taking calcidiol could partly reflect falling parathyroid hormone (PTH) levels with the supplement.
Declining BMD and attendant fracture risk have emerged as frequent complications of HIV infection and its treatment. Much research records low vitamin D levels in HIV-positive and negative populations, especially those with low yearly sun exposure. But research on how vitamin D supplementation affects BMD in people with HIV remains inconclusive. Despite significant 25-OH-D gains by 59 perinatally infected children taking 100,000 IU of oral cholecalciferol every 2 months and 1 g of calcium daily, the regimen did not improve bone mass accrual over 2 years [2].
The Madrid study involved 411 HIV-positive adults with at least two sequential measures of vitamin D (25-OH-D) and parathyroid hormone (PTH) and simultaneous DXA scanning to measure BMD. The investigators defined secondary hyperparathyroidism (excessive PTH secretion in response to low blood calcium) as PTH above 65 pg/mL. During follow-up, 97 people took 16,000 IU of oral calcidiol monthly after their vitamin D measurement, while the other 314 did not.
The 411 study participants averaged 44.6 years in age (range 39 to 50) and 308 (75%) were men. Body mass index averaged 23.9 kg/m2 (range 21.7 to 25.9). Most study participants, 89%, were Caucasian. The same proportion, 39%, became infected with HIV during sex between men and when injecting drugs, while the rest got infected during heterosexual sex. A relatively high proportion, 38%, had HCV infection, which is also tied to low BMD. Time since HIV diagnosis averaged 15.3 years (range 7.2 to 21.2).
All 411 people were taking antiretroviral therapy, including 75% taking tenofovir (linked to lower BMD) and 33% taking efavirenz (linked to falling vitamin D). Time taking the current regimen averaged 31 months (range 14.4 to 45.3). Baseline viral load averaged 3.5 log10 copies/mL (about 3000 copies), and median baseline CD4 count stood at 341 (range 211 to 503).
Overall 25-OH-D levels averaged 20.2 ng/mL and PTH 55.2 pg/mL. Among all study participants, 13% had 25-OH-D levels below 10 ng/mL, 57% below 20 ng/mL, and 85% below 30 ng/mL. In those three groups, prevalence of secondary hyperparathyroidism was 43%, 33%, and 19%. Serum levels of 25-OH-D were not associated with reduced BMD. Multivariate linear regression analysis found associations between older age (beta -0.3), lower body mass index (beta -0.25), and longer HIV infection (beta -0.25) and lower BMD.
Compared with people not taking calcidiol, the 97 people taking supplements were significantly older (average 46.3 versus 43.2 years, P < 0.01), had a lower average body mass index (23.2 versus 24.1 kg/m2, P = 0.02), had lower initial average 25-OH-D (14.9 versus 22.6 ng/mL, P < 0.01), had higher initial average PTH (63.4 versus 52.4 pg/mL, P < 0.01), had lower average initial femoral neck BMD (0.74 versus 0.78 g/cm2, P < 0.01), and had lower average initial lumbar BMD (0.87 versus 0.95 g/cm2, P < 0.01).
After 25-OH-D supplementation for a median 281 days, 25-OH-D levels rose significantly (12.8 versus 2.9 ng/mL without supplementation, P < 0.01) and PTH levels fell significantly (-7.2 versus -0.7 pg/mL, P = 0.04). Through a median 19.3 months in 85 people with successive DXA scans, those taking 25-OH-D gained hip BMD (+0.35%), whereas people not taking supplements lost hip BMD (-2.12%), though that difference fell short of statistical significance (P = 0.09). Respective changes in lumbar spine BMD were +0.57% and -1.36%.
Multivariate analysis adjusted for age, body mass index, CD4 count, initial BMD, HIV duration, and type and duration of antiretroviral therapy linked BMD improvement to calcidiol supplementation (beta 0.46, P < 0.01) and to falling PTH (beta -0.29, P = 0.04).
The researchers concluded that oral 25-OH-D supplementation improves BMD in people with HIV, a gain at least partly explained by the impact of 25-OH-D on PTH. Because this was not a randomized trial, it is possible that confounders not accounted for in the multivariate analysis could affect BMD change.
References
1. Banon S, Casado JL, Diaz de Santiago A, Moreno A, Perez-Elias MJ, Moreno S. Effect of monthly calcidiol supplementation on secondary hyperparathyroidism and bone mineral density in HIV infected patients with vitamin D deficiency. AIDS 2014. 20th International AIDS Conference. July 20-25, 2014. Melbourne. Abstract THPE046.
2. Arpadi SM, McMahon DJ, Abrams EJ, et al. Effect of supplementation with cholecalciferol and calcium on 2-y bone mass accrual in HIV-infected children and adolescents: a randomized clinical trial. Am J Clin Nutr. 2012;95:678-685.
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