In general, significantly elevated levels of CRP and PCT are closely associated with severity of infection (29); similarly, in this study, it was also found that the elevated levels of PCT and CRP in children with exogenous pulmonary ARDS were significantly higher than those in children with pulmonary ARDS, because exogenous pulmonary ARDS was mostly attributed to sepsis, and PCT level increased more obviously in sepsis caused by systematic infection. This evidence concerns the gene CRP and infection.