From the Guidelines
Liver function tests (LFTs) can be deranged in hospitalized patients due to numerous factors, with medication effects, infections, critical illness, nutritional factors, pre-existing liver conditions, surgical procedures, and hemodynamic changes being the most common causes. The most recent and highest quality study, 1, highlights that hepatocellular predominant abnormal liver function tests are reflected as an increase in aminotransferases, ALT, and AST, which can be caused by diffuse hepatic infiltration, acute hepatitis, or toxic or ischemic injury.
Common Causes of Deranged LFTs
- Medication effects: drugs like acetaminophen, antibiotics (particularly amoxicillin-clavulanate, fluoroquinolones), statins, antiepileptics (valproate, phenytoin), and anesthetics are frequently implicated, with dosages exceeding recommended limits increasing the risk, as noted in 1.
- Infections: viral hepatitis, sepsis, and COVID-19 are major contributors to LFT abnormalities, as mentioned in 1.
- Critical illness: hypoperfusion, hypoxia, and inflammatory responses can cause LFT abnormalities, as discussed in 1.
- Nutritional factors: both malnutrition and parenteral nutrition can potentially cause liver dysfunction, as highlighted in 1.
- Pre-existing liver conditions: fatty liver disease, cirrhosis, or autoimmune hepatitis may worsen during hospitalization, as noted in 1.
- Surgical procedures: particularly those involving the liver or biliary system, commonly cause transient LFT elevations, as mentioned in 1.
- Hemodynamic changes: heart failure or shock can lead to hepatic congestion or ischemic hepatitis, as discussed in 1.
Interpretation of Abnormal LFTs
The interpretation of abnormal liver chemistries must be taken in the clinical context of a given patient, as emphasized in 1. The initial evaluation of abnormal liver tests includes a detailed history, inventory of medications, and a physical examination, which should include an assessment of the patient’s risk factors for liver disease, medications, alcohol consumption, comorbid conditions, and signs and symptoms of hepatic disease, as recommended in 1. Understanding these factors is essential for proper interpretation of abnormal LFTs in hospitalized patients, allowing clinicians to distinguish between benign transient elevations and serious liver injury requiring intervention, as highlighted in 1.
From the Research
Factors that Derange Liver Function Tests (LFTs)
The following factors can derange liver function tests in a hospital setting:
- Acute hepatic dysfunction due to acute hepatitis, acute liver failure (ALF), and drug-induced liver injury (DILI) 2
- Exacerbations of pre-existing liver diseases (acute on chronic) and secondary liver injury during critical diseases such as sepsis, right heart failure, or cardiogenic shock, resulting in ischemic or hypoxic hepatitis 2
- Drug-related hepatotoxicity, secondary sclerosing cholangitis in critically ill patients (SC-CIP), or related to parenteral nutrition 2
- Statin use, which can cause dose-dependent borderline elevations of liver function tests over time 3
- Metabolic syndrome, which is positively associated with elevated levels of liver enzymes in older individuals 4
- Ageing, which impairs liver function and reduces the liver's regenerative capacity 4
Patterns of LFT Derangement
There are established patterns of LFT derangement, including:
- Cholestatic derangement
- Hepatocellular derangement
- Failure of synthetic function 5 These patterns can be used to identify the underlying cause of abnormal liver function tests.
Interpretation and Management of Abnormal LFTs
Abnormal liver function tests can be interpreted and managed using an algorithmic approach, which involves:
- Assessing the magnitude of enzymatic elevation
- Separating disease processes into hepatocellular, cholestatic, or functioning liver groupings
- Correlating laboratory findings to a patient's clinical presentation 6 Clinicians should also consider individual patient risk factors during the assessment of abnormal liver function tests 4