ALB and COVID-19: Contrary to the reduced values of albumin and vitamin D, D-dimer values higher than the obtained cut-off value of 0.50 ug/mL are characteristic of COVID-19 patients with severe clinical pictures (AUROC: 0.808, sensitivity: 79.7%, specificity: 72.0%, p < 0.0005), while values above 0.82 ug/mL may indicate a risk of a lethal disease outcome (AUROC: 0.733, sensitivity: 73.0%, specificity: 64.9%, p < 0.0005) (Figure 4C,D).