Dexamethasone treatment may mitigate adverse effects of vitamin D deficiency in hospitalized Covid-19 patients

Aims: We have previously demonstrated that vitamin D deficiency might be associated with worse outcomes in hospitalized Covid-19 patients. The aim of our study was to explore this relationship with dexamethasone therapy. Methods: We prospectively studied two cohorts of hospitalized Covid-19 patients between March and April and between September and December 2020 (n = 192). Patients were tested for serum 25-hydroxyvitamin D (25-OH-D) levels during admission. The first cohort not treated with dexamethasone (n = 107) was divided into vitamin D deficient (25-OH-D ≤ 30 nmol/L) (n = 47) and replete subgroups (25-OH-D > 30 nmol/L) (n = 60). The second cohort treated with dexamethasone (n = 85) was similarly divided into deficient (25-OH-D ≤ 30 nmol/L) (n = 27) and replete subgroups (25-OH-D > 30 nmol/L) (n = 58). Primary outcome was in-hospital mortality and secondary outcomes were elevation in markers of cytokine storm and ventilatory requirement. Results: No mortality difference was identified between cohorts and subgroups. The “no dexamethasone” cohort 25-OH-D deplete subgroup recorded significantly higher peak D-Dimer levels (1874 vs. 1233 µgFEU/L) (p = 0.0309), CRP (177 vs. 107.5) (p = 0.0055), and ventilatory support requirement (25.5% vs. 6.67%) (p = 0.007) compared to the replete subgroup. Among the 25-OH-D deplete subgroup higher peak neutrophil counts, peak CRP, peak LDH, peak ferritin, and lower trough lymphocyte counts were observed, without statistical significance. In the “dexamethasone” cohort, there was no apparent association between 25-OH-D deficiency and markers of cytokine storm or ventilatory requirement. Conclusion: Vitamin D deficiency is associated with elevated markers of cytokine storm and higher ventilatory requirements in hospitalized Covid-19 patients. Dexamethasone treatment appears to mitigate adverse effects of vitamin D deficiency.