Liver function blood tests (LFTs) are a group of tests that assess the health and performance of the liver by measuring the levels of enzymes, proteins, and substances produced or processed by the liver. These tests help in diagnosing liver diseases, monitoring liver damage, and evaluating how well treatments are working. Here are the most common liver function blood tests:

1. Alanine Aminotransferase (ALT)

  • Purpose: Measures the level of ALT, an enzyme found mostly in the liver.
  • Used for: Detecting liver cell injury, particularly in conditions like hepatitis, cirrhosis, and liver damage caused by medications or alcohol.

2. Aspartate Aminotransferase (AST)

  • Purpose: Measures the level of AST, an enzyme found in the liver, heart, and other organs.
  • Used for: Identifying liver damage; AST levels are often compared to ALT levels to differentiate between liver and other organ issues. The AST/ALT ratio is also used to assess the cause of liver damage (e.g., alcohol-related liver disease).

3. Alkaline Phosphatase (ALP)

  • Purpose: Measures the level of ALP, an enzyme found in the liver, bile ducts, and bones.
  • Used for: Detecting bile duct obstruction, liver disease, or bone disorders. Elevated ALP levels can indicate issues like cholestasis (blockage in bile flow) or liver tumours.

4. Gamma-Glutamyl Transferase (GGT)

  • Purpose: Measures the level of GGT, an enzyme found in the liver and bile ducts.
  • Used for: Assessing liver function and detecting bile duct problems or alcohol abuse. Elevated GGT levels often indicate liver or bile duct damage, and it is highly sensitive to alcohol-induced liver damage.

5. Bilirubin (Total and Direct)

  • Purpose: Measures the amount of bilirubin, a waste product from the breakdown of red blood cells.
  • Types:
    • Total Bilirubin: Measures the total amount of bilirubin in the blood.
    • Direct Bilirubin (Conjugated Bilirubin): Measures the form of bilirubin processed by the liver and ready for excretion.
  • Used for: Diagnosing jaundice (yellowing of the skin/eyes), liver disease, and bile duct blockages. Elevated bilirubin levels suggest liver dysfunction or issues with bile flow.

6. Albumin

  • Purpose: Measures the level of albumin, the main protein made by the liver.
  • Used for: Assessing liver function and nutritional status. Low albumin levels can indicate chronic liver disease (like cirrhosis), malnutrition, or kidney problems.

7. Total Protein

  • Purpose: Measures the total amount of proteins, including albumin and globulins, in the blood.
  • Used for: Assessing liver function, nutritional status, and overall health. Low total protein can indicate liver disease, kidney disease, or malnutrition.

8. Globulin

These tests give a comprehensive picture of liver health and are crucial in diagnosing liver diseases, such as hepatitis, cirrhosis, and fatty liver disease. They can also be used to monitor ongoing liver damage, guide treatment, and assess the impact of medications or toxins on the liver.

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