A Liver Function Test (LFT), often called a hepatic panel, is a common blood test used to evaluate the health of your liver. It measures the levels of specific enzymes and proteins that the liver releases when it is stressed, damaged, or functioning poorly.
Below is a detailed breakdown of what these tests measure and what the results typically mean.
When liver cells are injured or inflamed, these enzymes leak into the bloodstream.
ALT (Alanine Transaminase): Found primarily in the liver. High levels are a strong indicator of liver damage (e.g., hepatitis or fatty liver).
AST (Aspartate Transaminase): Found in the liver, but also in heart and muscle tissue. A high AST:ALT ratio (where AST is significantly higher) can sometimes suggest alcohol-related liver injury.
ALP (Alkaline Phosphatase): An enzyme related to the bile ducts. High levels often point to a blockage in the bile ducts or certain bone diseases.
GGT (Gamma-Glutamyl Transferase): Often used to confirm if a high ALP is coming from the liver. It is also very sensitive to alcohol consumption.
2. Liver Proteins (Indicators of Function)
These tests measure how well the liver is performing its "manufacturing" jobs.
Albumin: The main protein produced by the liver. Low levels can indicate chronic liver disease (like cirrhosis) or malnutrition.
Total Protein: Measures both albumin and globulins (which help fight infection).
Prothrombin Time (PT/INR): Measures how long it takes your blood to clot. Since the liver produces the proteins needed for clotting, a high PT/INR (slow clotting) suggests the liver is not functioning properly.
3. Bilirubin (Waste Product)
Bilirubin is a yellow substance produced during the breakdown of red blood cells.
Total Bilirubin: High levels cause jaundice (yellowing of the skin and eyes).
Direct (Conjugated) Bilirubin: High levels often suggest a "plumbing" problem, like a blocked bile duct.
Very high ALT and AST with slightly high ALP. This suggests direct damage to liver cells (like viral hepatitis).
Very high ALP and Bilirubin with slightly high ALT/AST. This suggests a problem with bile flow (like gallstones).
If only bilirubin is high but all other enzymes are normal, it may be a harmless genetic condition called Gilbert’s Syndrome.
