Association between vitamin D levels and inflammatory activity in brain death: A prospective study.

Background: Vitamin D insufficiency is linked to several common inflammatory disorders. Brain death (BD) causes a massive catecholamine release, leading to intense inflammatory activity. We aimed to evaluate vitamin D serum levels in brain-dead individuals in comparison to critically ill patients without BD to assess the correlation between vitamin D and cytokine levels.
Methods: Sixteen brain-dead patients and 32 critically ill controls were prospectively enrolled. Blood samples from 25 brain-dead patients from a previous study were also used for vitamin D quantification. Plasma TNF, IL-1β, IL-6, IL-8, IL-10, IFN-γ and serum vitamin D levels were compared using Student's t-test or one-way ANOVA. Spearman's test was used to assess the correlation between vitamin D and cytokine levels.
Results: Mean vitamin D levels were 16.4 ± 7.9 ng/mL, with 52 patients (71.2%) classified as vitamin D deficient (serum levels < 20 ng/mL). Vitamin D levels were similar in 41 brain-dead patients as compared to control subjects (15.6 ± 6.9 ng/mL vs 17.4 ± 9.0 ng/mL; p = 0.383). Moderate direct correlations were observed between vitamin D and IL-8, IL-10, and IFN-γ in the prospective group of 16 brain-dead patients (IL-8: r = 0.5, p = 0.049; IL-10 r = 0.67, p = 0.005; IFN-γ r = 0.6, p = 0.015). Vitamin D was inversely correlated with IL-6 (r = -0.36, p = 0.044) in critically ill controls.
Conclusions: Vitamin D serum levels were similarly low in brain-dead and critically ill patients. In brain-dead patients, vitamin D serum levels correlated with plasma IL-8, IL-10 and IFN-γ.
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