What type of specimen is typically required for liver function tests?

Liver function tests (LFTs) are a series of blood tests used to assess the health and performance of the liver. These tests measure several enzymes, proteins, and substances produced by the liver, indicating how well the liver is functioning and whether any liver damage has occurred.

Blood serum is the correct type of specimen for liver function tests because the measurements taken in these tests reflect the biochemical processes occurring within the liver. For example, enzymes such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are typically present in the blood, and their levels can indicate liver cell damage or inflammation. Additionally, substances like bilirubin and albumin are also measured in the serum, providing insights into liver function and synthetic capacity.

Other specimen types listed, such as urine, saliva, and sputum, are not suitable for these specific tests because they do not provide the necessary information about liver enzyme activity or liver function. Urine tests can indicate certain metabolic byproducts but do not directly reflect liver health. Saliva and sputum are also not relevant to liver function assessment, as they measure substances that are relevant to other bodily functions or conditions. Therefore, blood serum remains the standard and most effective specimen type for liver