IL6 and COVID-19: It has been reported that biomarkers such as CRP, ferritin, lactate dehydrogenase, D-dimer, IL-6, and fibrinogen may give an idea about the course of the disease in COVID-19 patients.26 C-reactive protein, an acute-phase protein, is synthesized by the liver in response to IL-6 and is a widely used biomarker of inflammation.