title: Alanine aminotransferase decreases with age: the Rancho Bernardo Study.
abstract: BACKGROUND
  Serum alanine aminotransferase (ALT) is a marker of liver injury. The 2005 American Gastroenterology Association Future Trends Committee report states that serum ALT levels remain constant with age. This study examines the association between serum ALT and age in a community-dwelling cohort in the United States.
  
  
  METHODS
  A cross-sectional study of 2,364 (54% female) participants aged 30-93 years from the Rancho Bernardo Study cohort who attended a research clinic visit in 1984-87. Demographic, metabolic co-variates, ALT, bilirubin, gamma glutamyl transferase (GGT), albumin, and adiposity signaling biomarkers (leptin, IL-6, adiponectin, ghrelin) were measured. Participants were divided into four-groups based upon age quartile, and multivariable-adjusted least squares of means (LSM) were examined (p for trend <0.05).
  
  
  RESULTS
  ALT decreased with increasing age, with mean ALT levels (IU/L) of 23, 21, 20, and 17 for those between quartile ages 30-62, 63-71, 72-77, and 78-93 years (p<0.0001). Trends of decreasing LSM ALT with age and the decreasing prevalence of categorically defined elevated serum ALT with age remained robust after adjusting for sex, alcohol use, metabolic syndrome components, and biomarkers of adiposity (p-value <0.0001), and was not materially changed after adjusting for bilirubin, GGT, and albumin.
  
  
  CONCLUSIONS
  ALT levels decrease with age in both men and women independent of metabolic syndrome components, adiposity signaling biomarkers, and other commonly used liver function tests. Further studies are needed to understand the mechanisms responsible for a decline in ALT with age, and to establish the optimal cut-point of normal ALT in the elderly.
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Mamie H
authors.initials: MH
authors.lastname: Dong
authors.forename: Ricki
authors.initials: R
authors.lastname: Bettencourt
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Barrett-Connor
authors.forename: Rohit
authors.initials: R
authors.lastname: Loomba
mesh_terms: D052242:Adiponectin / Q000096:biosynthesis; D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000410:Alanine Transaminase / Q000096:biosynthesis*; D000418:Albumins / Q000096:biosynthesis; D001663:Bilirubin / Q000096:biosynthesis; D002140:California; D015331:Cohort Studies; D005260:Female; D054439:Ghrelin / Q000096:biosynthesis; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis; D020738:Leptin / Q000096:biosynthesis; D008107:Liver Diseases / Q000175:diagnosis / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D005723:gamma-Glutamyltransferase / Q000096:biosynthesis
chemical_list: D052242:Adiponectin; D000418:Albumins; D054439:Ghrelin; D015850:Interleukin-6; D020738:Leptin; D005723:gamma-Glutamyltransferase; D000410:Alanine Transaminase; D001663:Bilirubin