title: Upper normal threshold of serum alanine aminotransferase in identifying individuals at risk for chronic liver disease.
abstract: OBJECTIVE
  Serum alanine aminotransferase (ALT) is an easily available, low-cost screening tool for detecting silent chronic liver disease. Recent studies have suggested that the currently accepted healthy ALT thresholds be lowered.
  
  
  METHODS
  In this retrospective cross-sectional study, we determined upper thresholds for ALT values in a nationally representative healthy cohort (n = 3337) from the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV). Sensitivity and specificity of the currently used ALT threshold (40 IU/L, regardless of gender) was compared against study-derived, gender-specific ALT thresholds for detecting individuals at risk for chronic liver disease in 27 913 health check-up participants.
  
  
  RESULTS
  The 95th percentile levels for ALT in healthy weight, metabolically normal, liver disease-free KNHANES participants were 34 IU/L for men and 25 IU/L for women. The prevalence of ALT elevation among health check-up participants was 11.0% in currently used thresholds, and increased to 22.6% with study-derived, gender-specific thresholds. Of the population who were additionally defined to have elevated ALT levels under new ALT threshold, 65.7% were at risk for chronic liver disease. Sensitivity for detecting individuals at risk for chronic liver disease improved from 18 to 33% with new thresholds whereas a trade-off in specificity (from 96 to 88%) was observed.
  
  
  CONCLUSIONS
  It is recommendable to lower the current ALT thresholds to better identify individuals at risk for chronic liver disease.
authors.affiliation: Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
authors.forename: Ha Na
authors.initials: HN
authors.lastname: Park
authors.forename: Dong Hyun
authors.initials: DH
authors.lastname: Sinn
authors.forename: Geum-Youn
authors.initials: GY
authors.lastname: Gwak
authors.forename: Jee Eun
authors.initials: JE
authors.lastname: Kim
authors.forename: Sang Youl
authors.initials: SY
authors.lastname: Rhee
authors.forename: Sung June
authors.initials: SJ
authors.lastname: Eo
authors.forename: Yu Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Moon Seok
authors.initials: MS
authors.lastname: Choi
authors.forename: Joon Hyeok
authors.initials: JH
authors.lastname: Lee
authors.forename: Kwang Cheol
authors.initials: KC
authors.lastname: Koh
authors.forename: Seung Woon
authors.initials: SW
authors.lastname: Paik
authors.forename: Byung Chul
authors.initials: BC
authors.lastname: Yoo
mesh_terms: D000328:Adult; D000368:Aged; D000410:Alanine Transaminase / Q000097:blood*; D044466:Asian People; D015415:Biomarkers / Q000097:blood; D002908:Chronic Disease; D004796:Clinical Enzyme Tests; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008107:Liver Diseases / Q000097:blood / Q000175:diagnosis* / Q000208:ethnology; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D011237:Predictive Value of Tests; D015995:Prevalence; D011379:Prognosis; D012016:Reference Values; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D015415:Biomarkers; D000410:Alanine Transaminase