How to Read and Understand Liver Function Test

Liver function tests (LFTs) are a group of blood tests that provide information about the state of your liver and its functionality. These tests also indicate the levels of enzymes and proteins that exist in your blood. They tell us how well the liver is performing its regular functions.  Here’s a breakdown of common LFT components and how to interpret them:

Key Components of Liver Function Tests

• Alanine Aminotransferase (ALT or SGPT): 
  • Normal Range: 7-56 units per liter.
  • Significance: High levels suggest liver inflammation or damage, as ALT is an enzyme found predominantly in the liver that helps the liver convert food into energy.
  • If the ALT levels are high. It indicates liver inflammation or damage.

• Aspartate Aminotransferase (AST or SGOT): 
  • Normal Range: 10-40 units per liter.
  • Significance: Like ALT, high levels indicate liver damage, but AST is also found in other organs like the heart and muscles. When liver cells are damaged, the level of AST in the blood becomes elevated.
  • If the AST levels are high. It indicates liver inflammation or damage.

• Alkaline Phosphatase (ALP):
  • Normal Range: 44-147 IU/L.
  • Significance: High levels can indicate bile duct obstruction, liver damage, or bone disorders.
  • If the ALP levels are high. It indicates bile duct obstruction or liver disease.

• Gamma-Glutamyl Transferase (GGT):
  • Normal Range: 0-51 IU/L.
  • Significance: Elevated GGT levels can indicate bile duct problems or alcohol abuse.
  • If the GGT levels are high. It indicates bile duct obstruction or liver disease more specific to liver issues.

• Total Bilirubin:
  • Normal Range: 0.1-1.2 mg/dL.
  • Significance: High levels cause jaundice and indicate liver’s reduced ability to process bilirubin, a byproduct of red blood cell breakdown.
  • If Bilirubin levels are high. It indicates jaundice and problems with liver’s ability to process and excrete bilirubin.

• Direct (Conjugated) Bilirubin:
  • Normal Range: 0-0.3 mg/dL.
  • Significance: Elevated levels suggest a problem with bilirubin processing or obstruction of bile flow.
  • If Direct Bilirubin levels are high. It indicates jaundice and problems with liver’s ability to process and excrete bilirubin.

• Albumin:
  • Normal Range: 3.5-5.0 g/dL.
  • Significance: Low levels may indicate chronic liver disease, as the liver synthesizes albumin.
  • If the Albumin levels are low. It indicates to chronic liver disease or other conditions affecting protein synthesis.

• Prothrombin Time (PT):
  • Normal Range: 11-13.5 seconds.
  • Significance: Prolonged PT may indicate liver damage, as the liver produces clotting factors.
  • If Prothrombin Time is prolonged. It suggests liver dysfunction affecting the production of clotting factors.

In addition to understanding Liver Function Test. We must also understand what are the common causes of Abnormal LFTs:

• Hepatitis: Viral, alcoholic, or autoimmune.

• Cirrhosis: Scarring of the liver often due to chronic alcohol use or hepatitis.

• Fatty Liver Disease: Due to obesity or alcohol use.

• Medications: Certain drugs can be the cause of liver damage.

• Bile Duct Obstruction: Gallstones or tumors blocking bile flow.

• Alcohol Abuse: Chronic alcohol consumption can lead to elevated liver enzymes.

Understanding your LFT results in context with your health and symptoms is crucial. Always consult with your doctor to interpret the results accurately and plan appropriate follow-up actions.