It is normal to have interleukin 6 in the body as it belongs to a group of cytokines in the body, but exceeding the reference range is mostly indicative of the occurrence of infections. Interleukin 6, present in the blood regulates and promotes the immune response, and is essentially a protein that improves immune function and protects against infection and inflammation, among other things. It is mainly produced by a variety of cells including macrophages, T cells, B cells and vascular endothelial cells. It is used along with interleukin 1 as an adjunct test to diagnose the occurrence of infections, i.e., inflammatory factors, especially inflammation due to bacterial infections, but interleukin 6 should not be relied upon alone to diagnose infectious diseases, as it is also elevated in the occurrence of tuberculosis, tumors, heart disease, and other immune disorders.