Abstract: Objective:To evaluate the diagnostic value of GAS6 in children with lower respiratory infection diseases and sepsis.Method:A total 240 hospitalized children including 54 subjects with sepsis,65 subjects with bacterial pneumonia,60 subjects with mycoplasma pneumonia,61 subjects with viral pneumonia and 55 normal controls were recruited in our study.The concentration of serum GAS6,PCT and CRP were assayed in the five groups.The values of serum GAS6,PCT and CRP were compared between the group of sepsis,bacterial pneumonia,mycoplasma pneumonia,viral pneumonia and normal control.Meanwhile,the ROC curves with GAS6,PCT and CRP were provided by the SPSS.Result:The serum concentration of GAS6 in the groups of sepsis,bacterial pneumonia and viral pneumonia were significantly higher than that of normal control group(P<0.05),but the GAS6 level showed no significant differences between the mycoplasma pneumonia and normal control groups(P>0.05).The GAS6 of patients with sepsis were significantly higher than that of patients with bacterial pneumonia,mycoplasma pneumonia and viral pneumonia(P<0.01).In addition,the GAS6 of patients with bacterial pneumonia was higher than that of patients with mycoplasma pneumonia and viral pneumonia(P<0.05),but the GAS6 level showed no significant differences between the viral pneumonia group and mycoplasma pneumonia group(P>0.05).Comparing the AUC of each index in diagnosis of sepsis and bacterial pneumonia,the AUC of GAS6 was less than PCT and CRP(P<0.05),but the AUC of GAS6 and PCT showed no significant differences in the diagnosis of viral pneumonia(P>0.05).Conclusion:The concentration of GAS6 in children patients with lower respiratory infection diseases and sepsis was significantly elevated,and it could not distinguish the pathogens in children patients with lower respiratory infection diseases.The PCT and CRP might have more diagnostic value than GAS6 in children patients with lower respiratory infection diseases and sepsis.