title: How do we interpret an elevated carbohydrate antigen 19-9 level in asymptomatic subjects?
abstract: OBJECTIVE
  This prospective cohort study aimed to evaluate the etiology of elevated CA 19-9 levels and to present appropriate guidelines for the asymptomatic patients.
  
  
  METHODS
  Between January 2004 and March 2007, we enrolled consecutive asymptomatic patients who had elevated CA 19-9 levels >37 U/mL. To evaluate the etiology, the CA 19-9 level was rechecked and further studies were carried out. If the CA 19-9 level decreased to the normal range, or if it showed a decreasing trend, then it was monitored annually. Yet, if the CA 19-9 level showed an increasing trend, then the level was monitored at intervals of 1, 3, and 6 months until no evidence of malignancy was proven.
  
  
  RESULTS
  Of the 62,976 patients, 501 (0.8%) subjects showed an elevated CA 19-9 level. This prospective analysis was conducted on 353 subjects (70.5%) who were followed up for at least 6 months. Ten patients (2.8%) were diagnosed with malignancies. There were 97 patients (27.5%) with benign diseases and 246 patients (69.7%) were deemed non-specific.
  
  
  CONCLUSIONS
  CA 19-9 should not be used as a screening tool. In the case of a persistently elevated CA 19-9 level, further work-up for determining the etiology should be done.
authors.affiliation: Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Republic of Korea.
authors.forename: B J
authors.initials: BJ
authors.lastname: Kim
authors.forename: K T
authors.initials: KT
authors.lastname: Lee
authors.forename: T G
authors.initials: TG
authors.lastname: Moon
authors.forename: P
authors.initials: P
authors.lastname: Kang
authors.forename: J K
authors.initials: JK
authors.lastname: Lee
authors.forename: J J
authors.initials: JJ
authors.lastname: Kim
authors.forename: J C
authors.initials: JC
authors.lastname: Rhee
mesh_terms: D000328:Adult; D000368:Aged; D001661:Biliary Tract Neoplasms / Q000175:diagnosis*; D014408:Biomarkers, Tumor / Q000097:blood*; D018395:CA-19-9 Antigen / Q000097:blood*; D002985:Clinical Protocols; D003627:Data Interpretation, Statistical; D005189:False Positive Reactions; D005260:Female; D005500:Follow-Up Studies; D017408:Guidelines as Topic; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000175:diagnosis*; D011446:Prospective Studies; D012016:Reference Values
chemical_list: D014408:Biomarkers, Tumor; D018395:CA-19-9 Antigen