Initial laboratory tests when evaluating for chronic liver disease
| Laboratory test | Function | Rationale |
|---|---|---|
| Complete blood cell count | Patients with liver disease are more prone to bleeding due to decrease production of liver clotting factors | May manifest as anemia |
| Often decreased platelet levels | ||
| Alanine aminotransferase (ALT)/aspartate aminotransferase (AST) | ALT is an enzyme found in the liver | ALT increased during liver injury |
| AST is an enzyme found in the liver, heart, muscle, and kidneys | AST increased in the presence of liver injury | |
| Elevated AST is less specific than ALT for liver injury | ||
| Albumin | Albumin is a protein made by the liver | Often decreased in chronic liver disease |
| Alkaline phosphatase | Alkaline phosphatase is an enzyme often produced by bile ducts, also produced by bone | May be normal or elevated in liver disease |
| Total bilirubin | Bilirubin, a breakdown product of heme, is conjugated by the liver to allow for removal from the body | May be increased in liver disease |
| Damage to the liver may result in inability to process bilirubin | ||
| Gamma-glutamyl transferase | An enzyme found primarily in the liver | May be elevated in liver disease |
| Can be used in elevated alkaline phosphatase to determine if origin is hepatic or bone | ||
| Prothrombin time (PT)/international normalized ratio (INR) | Measure amount and function of clotting factors | Because clotting factors are produced by the liver, PT and INR may be prolonged in patients with liver disease |