II. Background
- The term "Liver Function Test" or LFT is used for convenience and brevity, but is a misnomer
- The only true Liver Function Tests are those of synthetic function (e.g. INR)
- Transaminases are instead markers of hepatocellular disease
- Bilirubin and Alkaline Phosphatase are markers of cholestasis
- However, hepatology has failed to give the rest of us a convenient, more descriptive term to replace LFTs
- As with MASLD, they will no doubt replace LFT with a term twice as long, and more difficult to remember
III. Labs: Markers of liver function and Protein synthesis
- Serum Albumin
- Serum Bilirubin
- Prothrombin Time (PT/INR)
IV. Labs: Markers of hepatocellular disease
-
Alanine Aminotransferase (ALT)
- Most specific for hepatocyte injury
-
Aspartate Aminotransferase (AST)
- Less specific than ALT (present outside liver)
- AST to ALT ratio
- Most liver conditions (e.g. NASH): Ratio <1
- Alcoholism: Ratio >2
- Wilson's Disease >4
-
Lactate Dehydrogenase (LDH)
- Least specific for hepatocyte injury
- Dramatically increased in ischemic hepatitis
- Increased with alk phos in liver metastases
V. Labs: Markers of cholestasis
VI. Labs: Disease specific markers
- Definite value
- Viral Hepatitis Serology
- Iron studies
- Ceruloplasmin (Wilson's Disease)
- Limited value: Anti-Smooth Muscle Ab