LIVER FUNCTION TESTS: ALT, AST, Gamma GT, and Bilirubin

 

Why Liver Function Tests (LFTs)?

The liver is a large organ in your abdomen that is critical to your survival. It regulates many of the components in your blood by helping the body rid itself of poisons (toxins) and excess chemicals.

Your doctor will normally order LFTs during routine, annual checkups or if you have any symptoms of liver malfunction such as yellowed eyes/skin tone, or unusual fatigue.

 

Types of LFTs/Common Causes of Elevations:

 

ALT (alanine aminotransferase or formerly known as SGPT):

- ALT is an enzyme found in high concentrations in the liver and kidneys. It may also be found in the skeletal muscle, the heart, and the pancreas. Elevated levels can be important clues in helping diagnose both systemic and specific liver diseases.

- Common causes of high ALT levels include:

- Hepatitis

- Cirrhosis

- Infectious Mononucleosis

 

AST (asparate aminotransferase or formerly known as SGOT):

- AST is another enzyme found primarily in the liver and kidneys, but may also be found in other parts of the body.

- Common causes of high AST levels include:

- Heart Attack

- Infectious Mononucleosis

- Strenuous Exercise

- Liver Disease

- Hepatitis

- Trauma

 

Gamma GT:

- Gamma GT is an enzyme found in the liver and other organs.

- Common causes of high gamma GT levels include:

- Liver Disease

- Excessive alcohol use

- Blocked Bile Ducts (gallstones)

 

Bilirubin:

- Bilirubin is a yellow fluid found in bile as a result of normal and abnormal red blood cell destruction processes. As the red blood cells break down, bilirubin collects in the gallbladder.

- There are 2 types of bilirubin tests to diagnose levels:

 

Total or "Indirect" Bilirubin:

- This level increases in liver disease and in anemia (low numbers of red blood cells (RBC’s). The elevation of this level is caused by RBC’s being destroyed faster than they should (a process known as hemolysis).

 

Direct Bilirubin:

- Levels rise when the gallbladder is blocked, slowing or blocking the normal flow of bile fluid. These bile fluids aid in the digestion of food.

- Common causes of high bilirubin levels include:

- Gallbladder Disease

- Liver Disease

- Hemolytic Anemia (a blood disease with rapid red blood cell breakdown)

- Newborns who have a different blood type than their mother