Liver Function Tests: Enzymes and Liver Damage

Liver Function Tests

• Liver blood tests are used to assess liver functions or liver injury.
• An initial step in detecting liver damage is a simple blood test to determine the level of certain liver enzymes in the blood.

Enzymes and Their Functions

• Enzymes help to speed up (catalyze) routine and vital chemical reactions in the body.
• Under normal circumstances, liver enzymes mostly reside within the cells of the liver.
• When the liver is injured, these enzymes are spilled into the bloodstream.

Aminotransferase Enzymes

• Aminotransferases are sensitive and widely used liver enzymes.
• They include aspartate aminotransferase (AST or SGOT) and alanine aminotransferase (ALT or SGPT).
• These enzymes are normally contained within liver cells and to a lesser degree in muscle cells.
• If the liver is injured or damaged, liver cells spill these enzymes into the blood, raising the AST and ALT enzyme blood levels and signaling liver disease.

Functions of the Liver

• The liver has many vital functions, including:
  • Detoxification of blood
  • Production of important clotting factors, albumin, and other proteins
  • Metabolizing (processing) medications and nutrients
  • Processing of waste products of hemoglobin and other cells
  • Storing of vitamins, fat, cholesterol, and bile