Metabolic and histological features of non-alcoholic fatty liver disease patients with different serum alanine aminotransferase levels

Aliment Pharmacol Ther. 2009 Feb 15;29(4):387-96. doi: 10.1111/j.1365-2036.2008.03896.x. Epub 2008 Nov 17.


Background: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in affluent countries. Serum alanine aminotransferase (ALT) level is commonly performed to monitor NAFLD patients, but its clinical relevance is unclear.

Aim: To evaluate the metabolic and histological features of NAFLD patients with different ALT levels.

Methods: A total of 173 consecutive patients with biopsy-proven NAFLD were studied. Patients with persistently normal ALT and those with abnormal ALT were compared.

Results: Patients with persistently normal ALT had lower steatosis grade than patients with abnormal ALT, but they had similar degree of lobular inflammation, ballooning and fibrosis. Among 19 patients with ALT below 0.5 times the upper limit of normal (ULN) at the time of liver biopsies, 8 (42%) and 3 (16%) had steatohepatitis and significant fibrosis respectively. The within-patient coefficient of variance was similarly high in patients with simple steatosis and steatohepatitis (33.5). Age and glucose, but not ALT, were independent factors associated with significant fibrosis.

Discussion: Metabolic factors, but not ALT, are associated with histological severity. Patients with ALT < 0.5 x ULN may still have non-alcoholic steatohepatitis (NASH) and significant fibrosis. Evaluation of NAFLD patients should be based on metabolic risk factors, but not ALT level.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alanine Transaminase / metabolism*
  • Analysis of Variance
  • Anthropometry
  • Blood Glucose / metabolism*
  • Body Mass Index
  • Fatty Liver / enzymology*
  • Fatty Liver / pathology
  • Female
  • Humans
  • Insulin Resistance / physiology
  • Liver Cirrhosis / enzymology*
  • Liver Cirrhosis / pathology
  • Male
  • Middle Aged
  • Prospective Studies
  • Risk Factors
  • Severity of Illness Index
  • Surveys and Questionnaires


  • Blood Glucose
  • Alanine Transaminase