CRP and vitamin D deficiency: In the present study, CRP levels did not differ according to the vitamin D status of severe COVID-19 patients; however, other laboratory findings including the number of platelets, NLR, blood pH, PCT, lactate, urea, creatinine and LDH concentrations varied in the patients with vitamin D deficiency, suggesting that vitamin D status affects the inflammatory defense mechanisms against SARS-CoV-2.