title: Changes in the serum level of hepatitis B virus (HBV) surface antigen over the natural course of HBV infection.
abstract: BACKGROUND
  Despite its status as a potential biomarker of hepatitis B virus (HBV) response to interferon treatment, the changes in hepatitis B surface antigen (HBsAg) levels over the natural course of HBV carriers have not been analyzed sufficiently.
  
  
  METHODS
  A total of 101 HBV carriers were followed prospectively from 1999 to 2009. HBsAg level was measured yearly during the followed period.
  
  
  RESULTS
  HBsAg levels at baseline ranged from -1.4 to 5.32 log IU/ml, with a median value of 3.2 log IU/ml. Lower HBsAg levels were significantly associated with higher age and lower HBV replication status. The rate of change of HBsAg levels showed two peaks, with a cut-off value of -0.4 log IU/year. Based on this, patients were tentatively classified into rapid decrease (rate of change <-0.4 log IU/year) and non-rapid decrease groups. All baseline levels of HBsAg, HB core-related Ag, and HBV DNA were lower in the rapid decrease group than in the non-rapid decrease group. Patients with persistently positive HBeAg were all classified into the non-rapid decrease group. In patients with persistently negative HBeAg, HBV DNA levels were significantly (P = 0.028) lower in the rapid decrease group than in the non-rapid decrease group.
  
  
  CONCLUSIONS
  Lower baseline HBsAg levels were significantly associated with older age and lower viral activity. Both a loss of HBeAg detection as well as inactive replication of HBV are suggested to be fundamental factors contributing to a rapid decrease in HBsAg over the natural course of HBV infection.
authors.affiliation: Department of Medicine, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Matsumoto
authors.forename: Eiji
authors.initials: E
authors.lastname: Tanaka
authors.forename: Susumu
authors.initials: S
authors.lastname: Morita
authors.forename: Kaname
authors.initials: K
authors.lastname: Yoshizawa
authors.forename: Takeji
authors.initials: T
authors.lastname: Umemura
authors.forename: Satoru
authors.initials: S
authors.lastname: Joshita
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis / Q000821:virology; D002353:Carrier State / Q000175:diagnosis / Q000821:virology; D015331:Cohort Studies; D004279:DNA, Viral / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006509:Hepatitis B / Q000175:diagnosis* / Q000821:virology; D006512:Hepatitis B Core Antigens / Q000097:blood; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D006513:Hepatitis B e Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000235:genetics / Q000276:immunology*; D006801:Humans; D008113:Liver Neoplasms / Q000175:diagnosis / Q000821:virology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D055815:Young Adult
chemical_list: D004279:DNA, Viral; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens