title: Role of hepatitis B surface antigen (HBsAg) in identifying true inactive HBsAg carriers infected with genotype C hepatitis B virus.
abstract: BACKGROUND
  Inactive and active phases of hepatitis B e antigen-negative chronic hepatitis B virus (HBV) infection are diagnosed by serum HBV DNA levels, with cutoff at 2000 IU/mL. However, it is difficult to distinguish inactive carriers at a single time point because HBV DNA levels can transiently decrease to <2000 IU/mL even in noninactive carriers.
  
  
  OBJECTIVE
  We aimed to establish the role of serum hepatitis B surface antigen (HBsAg) in identifying "true inactive carriers" among treatment-naive genotype C HBV-infected patients with low viremia.
  
  
  METHODS
  A total of 133 hepatitis B e antigen-negative carriers with serum HBV DNA levels of <2000 IU/mL and normal alanine aminotransferase levels were enrolled and followed up for >12 months.
  
  
  RESULTS
  Forty patients (30.1%) were classified as noninactive carriers (HBV DNA ≥2000 IU/mL and/or alanine aminotransferase >40 IU/L) during 12 months from enrollment. No baseline serum HBV DNA levels could identify true inactive carriers with 100% specificity, whereas baseline serum HBsAg levels (50 IU/mL) identified true inactive carriers with 100% specificity and 29% detection rate. Detection rate increased when different cutoff levels were applied to different age groups according to median age (46 y). It was comparable in both younger and older groups (37.2% vs. 38%) even when HBsAg cutoff level was increased in the former (400 vs. 50 IU/mL). Furthermore, none reversed to noninactive phase during long-term follow-up when these cutoff levels were applied.
  
  
  CONCLUSIONS
  Baseline serum HBsAg levels at a single time point can identify persistently true inactive carriers, with different cutoff levels according to age.
authors.affiliation: Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea.
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Yim
authors.forename: Soon Ho
authors.initials: SH
authors.lastname: Um
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Jung
authors.forename: Yeon Seok
authors.initials: YS
authors.lastname: Seo
authors.forename: Hyung Joon
authors.initials: HJ
authors.lastname: Yim
authors.forename: Ho Sang
authors.initials: HS
authors.lastname: Ryu
authors.forename: Hoon Jai
authors.initials: HJ
authors.lastname: Chun
authors.forename: Yoon Tae
authors.initials: YT
authors.lastname: Jeen
authors.forename: Chang Duck
authors.initials: CD
authors.lastname: Kim
authors.forename: Bora
authors.initials: B
authors.lastname: Keum
authors.forename: Hong Sik
authors.initials: HS
authors.lastname: Lee
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000410:Alanine Transaminase / Q000097:blood; D019540:Area Under Curve; D002353:Carrier State / Q000097:blood* / Q000175:diagnosis*; D004279:DNA, Viral / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D005838:Genotype; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D006513:Hepatitis B e Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000097:blood* / Q000175:diagnosis* / Q000821:virology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D013997:Time Factors; D055815:Young Adult
chemical_list: D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens; D000410:Alanine Transaminase