Clinicians are required to assess abnormal liver chemistries on a daily basis.
Dr Paul Kwo and colleagues from California, USA reviewed the ACG clinical guidelines to evaluate abnormal liver chemistries.
The team report that the most common liver chemistries ordered are serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and bilirubin.
These tests should be termed liver chemistries or liver tests.
Hepatocellular injury is defined as disproportionate elevation of AST and ALT levels compared with alkaline phosphatase levels.
The guidelines also define cholestatic injury as disproportionate elevation of alkaline phosphatase level as compared with AST and ALT levels.
|A history of prescribed and over-the-counter medicines should be sought|
|American Journal of Gastroenterology|
The majority of bilirubin circulates as unconjugated bilirubin, and an elevated conjugated bilirubin implies hepatocellular disease or cholestasis.
The team identified multiple studies that demonstrate an elevated ALT is associated with increased liver-related mortality.
The researchers report that a true healthy normal ALT level ranges from 29 to 33 IU/l for males, 19 to 25 IU/l for females and levels above this should be assessed.
The degree of elevation of ALT and or AST in the clinical setting helps guide the evaluation.
The team note that evaluation of hepatocellular injury includes testing for viral hepatitis A, B, and C, assessment for nonalcoholic fatty liver disease and alcoholic liver disease, screening for hereditary hemochromatosis, autoimmune hepatitis, Wilson’s disease, and alpha-1 antitrypsin deficiency.
In addition, a history of prescribed and over-the-counter medicines should be sought.
For the evaluation of an alkaline phosphatase elevation determined to be of hepatic origin, testing for primary biliary cholangitis and primary sclerosing cholangitis should be undertaken.
The team report that total bilirubin elevation can occur in either cholestatic or hepatocellular diseases.
The guidelines recommend that elevated total serum bilirubin levels should be fractionated to direct and indirect bilirubin fractions, and an elevated serum conjugated bilirubin implies hepatocellular disease or biliary obstruction in most settings.
A liver biopsy may be considered when serologic testing and imaging fails to elucidate a diagnosis, to stage a condition, or when multiple diagnoses are possible.
Dr Kwo's team concludes, "This review is designed for physicians in gastroenterology and hepatology as well as physician assistants, nurse practitioners and other advanced-practice healthcare professionals interested in the latest information on diagnostic GI and state-of-the-art treatment of these illnesses."
"Clinicians will be able to evaluate patients with abnormal liver tests according to current ACG guidelines."