From the Guidelines
Liver function tests (LFTs) are not necessary for routine admission screening and should be ordered selectively based on clinical indications. This approach is supported by the guidelines on the management of abnormal liver blood tests, which suggest that LFTs should be used to determine the likelihood of liver fibrosis in patients with non-alcoholic fatty liver disease (NAFLD) or liver disease of unknown etiology 1. The study found that initial assessment includes calculation of a FIB4 or NAFLD fibrosis score, and second-line tests such as serum markers and imaging modalities should be considered.
Key Points to Consider
- Routine LFTs in all admissions can lead to unnecessary testing, increased healthcare costs, and potential false positives requiring further investigation.
- Clinicians should order LFTs when patients present with symptoms suggesting liver disease, have a history of liver conditions, are taking hepatotoxic medications, have alcohol use disorder, or when baseline values are needed before starting potentially hepatotoxic treatments.
- A study published in 2020 found that abnormal LFTs were reported in approximately 15% of patients with COVID-19, but the abnormalities were not consistently reported across studies and were often attributable to secondary effects rather than primary virus-mediated hepatocellular injury 1.
- The standard liver panel typically includes alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), bilirubin, and albumin, providing information about hepatocellular damage, cholestasis, and synthetic function.
Clinical Implications
- The targeted approach to ordering LFTs ensures appropriate resource utilization while still identifying clinically significant liver abnormalities.
- Clinicians should be cautious when interpreting LFT results and consider the clinical context and potential causes of abnormal results.
- Further evaluation should be performed to investigate non-COVID-19 causes of liver disease in patients with abnormal LFTs.
From the Research
Liver Function Tests (LFTs) in Routine Admission Screening
- The necessity of LFTs in routine admission screening is a topic of discussion among medical professionals, with some studies suggesting that they may not be entirely necessary for asymptomatic patients 2, 3.
- LFTs are a panel of blood markers used to assess and monitor several diseases, but they are not all true tests of liver function, and abnormalities may not reflect liver disease 3.
- The most efficient screening tests for liver damage are alanine transaminase, alkaline phosphatase, and bilirubin, and repeat testing when results are abnormal, and use of ancillary tests, such as creatine phosphokinase or gamma-glutamyl-transferase, may confirm liver damage 2.
Interpretation of Abnormal LFT Results
- Incidentally detected abnormality in LFTs is a common situation encountered by physicians, and many of these patients do not have primary liver disease as most of the commonly performed markers are not specific for the liver and are affected by myriad factors unrelated to liver disease 4.
- A combination of a careful history and clinical examination along with interpretation of pattern of liver test abnormalities can often identify type and aetiology of liver disease, allowing for a targeted investigation approach 4.
- Severity of liver injury is best assessed by composite scores like the Model for End Stage Liver Disease rather than any single parameter 4.
Cost-Effectiveness of LFTs in Primary Care
- A cost-minimisation analysis based on a comprehensively tested cohort found that testing all patients for viral hepatitis without repeating LFTs was more efficient than the current guidelines, which advocate for repeating the LFT with a view to testing for specific disease if it remained abnormal 5.
- A selective strategy of viral testing all patients for viral hepatitis if they were born in countries where viral hepatitis was prevalent provided high efficiency with little loss of sensitivity 5.