Liver Function Test - All You Need to Know

Liver function tests are blood tests that help the physician to diagnose and monitor liver disease or liver damage by measuring the levels of certain enzymes and proteins in the blood.

The symptoms of liver damage include the following:

? Lack of appetite

? Nausea or vomiting

? Weakness or feeling very tired

? Yellowish eyes or skin (jaundice)

? Dark urine or light-colored feces (less common)

? Swollen belly (less common)

Alanine transaminase (ALT). ALT is an enzyme found almost exclusively in the liver that helps to break down proteins into energy for the liver cells. When there is acute liver damage, ALT is released into the bloodstream and levels increase.

Aspartate transaminase (AST). AST is an enzyme predominantly found in the liver (but also seen in kidneys, pancreas, heart, skeletal muscle, and red blood cells), that helps metabolize amino acids. Like ALT, AST is normally present in blood at low levels. An increase in AST levels may indicate liver damage, liver disease or muscle damage.

Alkaline phosphatase (ALP). ALP is an enzyme found in the liver and bone and is important for breaking down proteins. Higher-than-normal levels of ALP may indicate liver damage or diseases, such as a blocked bile duct (caused by tumor, abscess etc.), or certain bone diseases.

Albumin and Total Protein. Albumin is one of several proteins made in the liver. Your body needs these proteins to fight infections and perform other functions. Lower-than-normal levels of albumin and total protein may indicate liver damage or disease.

Bilirubin. Bilirubin is a substance produced during the normal breakdown of red blood cells. Bilirubin passes through the liver and is excreted in the stool. Elevated levels of bilirubin (jaundice) might indicate liver damage or disease or certain types of anemia.

Gamma-glutamyltransferase (GGT). GGT is an enzyme in the blood. Higher levels may indicate liver or bile duct damage and is also an indicator of alcohol ingestion (alcoholic liver disease).

L-lactate dehydrogenase (LDH). Lactic dehydrogenase is a type of protein (also called an isoenzyme) that is involved in the body's metabolic process. Elevated levels may indicate liver damage but can be elevated in many other disorders.