OBJECTIVE To investigate the relationship of the serum carbohydrate antigen with the severity of idiopathic interstitial pneumonia(IIP),so as to guide the judgment of the prognosis of IIP patients.METHODS Totally 46 cases of patients with bacterial pneumonia during Jan.2007 to Dec.2013 were taken as the control group,another 46 cases of IIP patients as the study group.Levels of serum carbohydrate antigen 12-5(CA12-5),carbohydrate antigen 15-3(CA15-3),and carbohydrate antigen 19-9(CA19-9)were compared before...