Chapter 10.2 LIVER FUNCTION TESTS
Topic: Liver Function Test
The liver is a large organ located in the upper right-hand part of the abdomen behind the lower ribs. It takes up drugs and toxic substances from the blood and renders them harmless. It produces proteins, including enzymes and blood clotting factors, helps maintain hormone balance and stores vitamins. The liver produces bile, a fluid that is transported through ducts to the gallbladder to be stored and then to the small intestine to help digest fats.
Liver disease can be detected, evaluated and monitored by combinations of up to five tests measured at the same time on a blood sample. These may include:
- Alanine aminotransferase (ALT) – an enzyme mainly found in the liver; the best test for detecting hepatitis.
- Aspartate aminotransferase (AST) – an enzyme found in the liver and a few other places, particularly the heart and other muscles in the body.
- Total bilirubin – measures all the yellow bilirubin pigment in the blood.
- Conjugated bilirubin- measures the form made only in the liver and is often requested with total bilirubin in infants with jaundice.
- Alkaline phosphatase (ALP) – an enzyme related to the bile ducts; often increased when they are blocked, either inside or outside the liver.
- Albumin – measures the main protein made by the liver and tells how well the liver is making this protein.
- Total protein – measures albumin and all other proteins in blood, including antibodies made to help fight off infections
Other tests that can help to assess the liver include gamma-glutamyl transferase (GGT), prothrombin time (PT), P3NP, ELF and sometimes urine testing.