title: Follow-up of mild alanine aminotransferase elevation identifies hidden hepatitis C in primary care.
abstract: BACKGROUND
  Hepatitis C (HCV) and hepatitis B (HBV) virus infection can lead to serious complications if left untreated, but often remain undetected in primary care. Mild alanine aminotransferase (ALT) elevations (30-100 IU/l) are commonly found and could be associated  with viral hepatitis; unfortunately, these findings frequently remain without follow-up.
  
  
  OBJECTIVE
  To determine if and how mild ALT elevation can be used to identify hidden HCV and HBV infection in primary care.
  
  
  METHODS
  Primary care patients referred  for liver enzyme testing were selected by a large primary care Diagnostic Centre (Saltro).
  
  
  METHODS
  First, 750 anonymous samples were collected in three categories of ALT elevation (30-50 IU/l, 50-70 IU/l, and 70-100 IU/l) and tested for HCV and HBV. Second,  the national prevalence of each ALT elevation was estimated by analysing all annual ALT tests performed at Saltro.
  
  
  RESULTS
  HCV prevalence was 1.6% and 1.2% in patients with an ALT of 50-70 IU/l and 70-100 IU/l respectively. In patients with an ALT of 30-50  IU/l, HCV prevalence was normal (≤0.1%). HBV prevalence was normal (≤0.4%) in all groups. The estimated number of ALT tests performed nationally each year in primary care was 1.1 million. An ALT of 30-50 IU/l was found in 21.1%, an ALT of 50-70 IU/l in 5.6%, and 2.6% had  an ALT of 70-100 IU/l.
  
  
  CONCLUSIONS
  In primary care patients with an ALT level of 50-100 IU/l, HCV prevalence is tenfold the population prevalence, whereas HBV prevalence is not elevated. Therefore, diagnostic follow-up for HCV is indicated in these patients,  even when other explanations for ALT elevation are present.
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, The Netherlands. c.helsper@gmail.com
authors.forename: Charles
authors.initials: C
authors.lastname: Helsper
authors.forename: Gerrit
authors.initials: G
authors.lastname: van Essen
authors.forename: Bernard D
authors.initials: BD
authors.lastname: Frijling
authors.forename: Niek J
authors.initials: NJ
authors.lastname: de Wit
mesh_terms: D000410:Alanine Transaminase / Q000378:metabolism*; D003430:Cross-Sectional Studies; D042241:Early Diagnosis; D005194:Family Practice; D005260:Female; D019694:Hepatitis B, Chronic / Q000175:diagnosis* / Q000453:epidemiology; D019698:Hepatitis C, Chronic / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors
chemical_list: D000410:Alanine Transaminase