Letter to the editor: Vitamin D levels in acute illness and clinical severity in COVID-19 patients.

We would like to comment on the recently published article titled: "Circulating Vitamin D levels status and clinical prognostic indices in COVID-19 patients" by Ricci et al. The authors grouped the patients into two groups according to the vitamin D levels measured at the time of admission into the hospital and reported that lower vitamin D levels are associated with elevated D-dimer and IL-6 levels, low CD4/CD8 ratio and compromised clinical findings with elevated LIPI and SOFA scores. However, review of recent literature shows this association to be debatable. The 25-hydroxyvitamin D levels in the initial phase of critical illness have been reported to drop rapidly and hence consideration of the time of measurement from symptom onset would have enhanced the clinical relevance of these findings. Inferred association between vitamin D levels and disease severity based on SOFA score in COVID-19 patients, needs to be further explored in the light of the recent literature which casts doubt on using SOFA score at admission to predict mortality in COVID-19.