What type of samples are typically used for liver enzyme tests?

Serum samples are the standard choice for liver enzyme tests due to their ability to provide clear and accurate measurements of enzyme levels released into the bloodstream as a result of liver activity and damage. Liver enzymes like alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are primarily assessed through serum analysis because these enzymes are typically present in higher concentrations in the serum compared to other biological fluids.

Liver enzyme tests measure these enzymes to evaluate liver health and function, as well as to identify liver diseases or conditions. Serum, being the clear part of the blood obtained after clotting, is suitable for this purpose as it allows for the detection of soluble enzymes without interference from other cellular components, which may be present in whole blood samples.

While urine and saliva can provide some information for other laboratory tests, they are not the appropriate mediums for accurately assessing liver enzyme levels. Urine primarily reflects renal function, while saliva does not typically contain significant levels of liver enzymes in a manner that would allow for effective diagnostics of liver diseases.