Interleukin-6, referred to as IL-6, is a cytokine and belongs to the category of interleukin. IL-6 can regulate immune response, acute phase response and hematopoietic function, and play an important role in the body's anti-infective immune response. When infection and inflammation occur, IL-6 is first generated and the level rises rapidly, reaching a peak at 2 hours. Its elevation is consistent with the severity of the infection and induces procalcitonin (PCT) and CRP in the infection which started to rise after 2h and 6h. The increase of IL-6 is positively correlated with the severity of the disease, and the increased magnitude reflects the severity of the disease.