Upper limit of normal serum alanine aminotransferase levels in <scp>J</scp>apanese subjects

<jats:sec><jats:title>Aim</jats:title><jats:p>Serum alanine aminotransferase (<jats:styled-content style="fixed-case">ALT</jats:styled-content>) is important for screening, diagnosis and management of chronic liver diseases. The incidence of non‐alcoholic fatty liver disease (<jats:styled-content style="fixed-case">NAFLD</jats:styled-content>)/non‐alcoholic steatohepatitis (<jats:styled-content style="fixed-case">NASH</jats:styled-content>), which is considered a hepatic manifestation of lifestyle‐related diseases, is increasing worldwide. However, the upper limit of the normal <jats:styled-content style="fixed-case">ALT</jats:styled-content> level has not yet been established because of not excluding many lifestyle‐related diseases. The aim of this study was to evaluate the upper limit of normal serum <jats:styled-content style="fixed-case">ALT</jats:styled-content> levels in <jats:styled-content style="fixed-case">J</jats:styled-content>apanese subjects.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>We analyzed the serum <jats:styled-content style="fixed-case">ALT</jats:styled-content> levels of 11 404 <jats:styled-content style="fixed-case">J</jats:styled-content>apanese subjects negative for hepatitis <jats:styled-content style="fixed-case">B</jats:styled-content> surface antigen and hepatitis <jats:styled-content style="fixed-case">C</jats:styled-content> virus antibody, and who received health check‐ups. Lifestyle factors related to <jats:styled-content style="fixed-case">ALT</jats:styled-content> levels were determined by multivariate analysis. Subjects with all factors identified by multivariate analysis within the normal range were defined as “healthy” subjects. The 90th percentile of <jats:styled-content style="fixed-case">ALT</jats:styled-content> levels in healthy subjects was defined as the upper limit of normal <jats:styled-content style="fixed-case">ALT</jats:styled-content>.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Whereas alcohol intake was not a significant factor, the following were independently associated with <jats:styled-content style="fixed-case">ALT</jats:styled-content> concentration by multivariate analysis: sex; age; body mass index; waist circumference; concentrations of total cholesterol, high‐density lipoprotein cholesterol, triglycerides and fasting blood glucose; and fatty liver on ultrasonography. Healthy subjects consisted of 1462 (21.2%) men and 2046 (45.4%) women, and the 90th percentiles of the <jats:styled-content style="fixed-case">ALT</jats:styled-content> levels in the two groups were 29 and 23 IU/L, respectively.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>The upper limits of normal <jats:styled-content style="fixed-case">ALT</jats:styled-content> when considering lifestyle factors in Japanese subjects were 29 IU/L in men and 23 IU/L in women.</jats:p></jats:sec>