Your liver is a chemical powerhouse — it processes nutrients, filters toxins, and makes proteins. When liver cells are stressed or damaged, they release enzymes into the blood. A liver function test (LFT) measures these to gauge liver health.
The Main Liver Enzymes
- ALT (Alanine Aminotransferase) — the most liver-specific enzyme. A raised ALT usually points to the liver itself.
- AST (Aspartate Aminotransferase) — found in the liver but also muscle and heart, so it's interpreted alongside ALT.
- ALP (Alkaline Phosphatase) — rises with bile-duct problems and bone activity.
- GGT — sensitive to alcohol and bile-duct issues; a high GGT with high ALP points to the bile system.
- Bilirubin & Albumin — reflect how well the liver is actually doing its job.
What the Pattern Reveals
Doctors look at which enzymes are up and by how much. A high ALT and AST with normal ALP suggests liver-cell irritation ("hepatocellular" pattern) — commonly from fatty liver, viral hepatitis, alcohol, or medications. A high ALP and GGT with milder ALT points to the bile ducts ("cholestatic" pattern).
The Most Common Cause Today
Non-alcoholic fatty liver disease is now the leading reason for mildly elevated enzymes, closely tied to weight, diabetes, and cholesterol. The good news: it often improves with diet, exercise, and weight loss.
When to Be Concerned
Very high enzymes (many times the upper limit), rising bilirubin, jaundice (yellow eyes or skin), or a falling albumin all warrant prompt evaluation. In regions with high hepatitis B and C prevalence, persistent elevations should always be investigated.
Make Sense of Your LFTs
Upload your liver panel to Lab Lens for a clear explanation of your ALT, AST, and other liver markers.