New ACG Guideline Defines Normal Serum ALT Levels

For the first time in a liver test guideline, authors have defined a normal health serum serum alanine aminotransferase level

The American College of Gastroenterology has issued new recommendations on the evaluation of abnormal liver chemistries defining a normal healthy serum alanine aminotransferase (ALT) level for women and men and recommending that levels above this should be evaluated by physicians. 

For the first time in a liver test guideline, the authors have defined a normal health serum ALT level to be up to 25 IU/L for women and up to 33 IU/L for men. These levels were based on available literature correlating ALT levels and liver-related mortality. The upper limit of normal levels for ALT tend to differ from institution to institution, and clinicians may not think to assess an ALT level of 70 IU/L though this elevation is associated with increased liver-related mortality.  

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“However, clinical judgment still remains of paramount importance,” noted the authors.

Overall, the guideline offers a framework for physicians to approach patients with the common issue of abnormal liver chemistries. A step-wise approach is presented for the evaluation of elevated aminotransferase (ALT/AST), alkaline phosphatase, and bilirubin levels including appropriate historical questions, important physical examination findings, laboratory, radiological evaluation, and liver biopsy if required. Growing evidence over the past 10 years had shown that ALT levels higher than the defined thresholds were associated with greater liver-related mortality rates across the world, “including populations from the United States, Europe, and Asia, that is driven by the obesity epidemic.” 

The ACG Abnormal Liver Chemistries Guideline also includes algorithms utilizing a graded approach to those with elevated aminotransferase elevations by categorizing them as minimal, mild, moderate, and severe. If liver chemistries do not normalize, specific guidelines as to when an immediate vs. limited evaluation is needed are also given. Additional algorithms on evaluating abnormal alkaline phosphatase and bilirubin levels are provided, including suggested serologic and radiologic evaluations as well as when liver biopsy should be considered. 

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