From the Guidelines
Liver function tests (LFTs) are a group of blood tests that measure various enzymes, proteins, and substances produced or processed by the liver to assess its health and function, with abnormal results indicating potential liver damage or disease, as seen in studies such as 1 and 1. The standard LFT panel typically includes:
- Alanine aminotransferase (ALT)
- Aspartate aminotransferase (AST)
- Alkaline phosphatase (ALP)
- Gamma-glutamyl transferase (GGT)
- Bilirubin
- Albumin
- Total protein These tests help diagnose liver diseases, monitor liver function during medication use, and track progression of known liver conditions, with elevated ALT and AST suggesting liver cell damage, while high ALP and GGT may indicate bile duct problems, as noted in 1. Increased bilirubin can cause jaundice, and low albumin might signal chronic liver disease, as seen in 1. The test requires a simple blood draw, usually after fasting for 8-12 hours, with normal ranges varying by laboratory, age, and gender. If abnormal results occur, your doctor may recommend additional tests like ultrasound, CT scan, or liver biopsy to determine the underlying cause, as recommended in 1. Regular monitoring of liver function is particularly important for patients taking hepatotoxic medications or those with chronic liver conditions, as emphasized in 1 and 1. It is essential to note that normal liver blood tests do not exclude non-alcoholic fatty liver disease (NAFLD) or significant fibrosis, as highlighted in 1, and persistently unexplained abnormal liver blood tests should always be investigated.
From the FDA Drug Label
Abnormalities in liver enzymes have not been associated with Ursodiol therapy and, in fact, Ursodiol has been shown to decrease liver enzyme levels in liver disease. However, patients given Ursodiol should have SGOT (AST) and SGPT (ALT) measured at the initiation of therapy and thereafter as indicated by the particular clinical circumstances
The results of the liver function test (LFT) are not explicitly stated, but liver enzyme levels have been shown to decrease in patients with liver disease taking Ursodiol. Patients should have SGOT (AST) and SGPT (ALT) measured at the initiation of therapy and as indicated by clinical circumstances 2.
From the Research
Liver Function Test (LFT) Results
The results of a liver function test (LFT) can indicate various conditions, including hepatocellular injury, cholestatic injury, and liver disease. The most common liver chemistries ordered are serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, and bilirubin 3.
Types of Liver Injury
- Hepatocellular injury is defined as disproportionate elevation of AST and ALT levels compared with alkaline phosphatase levels 3.
- Cholestatic injury is defined as disproportionate elevation of alkaline phosphatase level as compared with AST and ALT levels 3.
Interpretation of LFT Results
- Elevated ALT levels have been associated with increased liver-related mortality 3.
- The degree of elevation of ALT and/or AST in the clinical setting helps guide the evaluation 3.
- Total bilirubin elevation can occur in either cholestatic or hepatocellular diseases, and elevated serum conjugated bilirubin implies hepatocellular disease or biliary obstruction in most settings 3.
Associated Conditions
- Abnormal liver function tests can be associated with various conditions, including alcohol-related liver disease, non-alcoholic fatty liver disease, viral hepatitis, and autoimmune hepatitis 4, 3, 5, 6.
- Being overweight is another increasingly common cause of abnormal liver enzyme levels, and adiposity may also increase the impact of ethanol consumption on liver pathology 4.
Diagnostic Approaches
- Liver enzyme measurements can serve as indicators of general health and the status of oxidative stress in vivo 4.
- A liver biopsy may be considered when serologic testing and imaging fail to elucidate a diagnosis, to stage a condition, or when multiple diagnoses are possible 3.
- Community pathways have been generated for the early detection and risk stratification of chronic liver disease, focusing on abnormal liver function tests and targeting groups at greater risk of chronic liver disease 5.