ALT (Alanine Transaminase) is a blood test that measures alt (alanine transaminase) levels in the blood. Normal range: Men: < 40 U/L · Women: < 35 U/L (typical Australian pathology reference range). It is commonly used to aLT is the first enzyme to rise in hepatocellular liver injury — including non-alcoholic fatty liver disease (NAFLD), vi...
What is ALT (Alanine Transaminase)?
ALT (Alanine Transaminase, also written ALAT or SGPT) is an enzyme concentrated in the liver. When liver cells are damaged, ALT leaks into the bloodstream, so it is the single most liver-specific enzyme on a standard Liver Function Test (LFT). It is often interpreted alongside AST, GGT and ALP to build a picture of liver health.
Why is it measured?
ALT is the first enzyme to rise in hepatocellular liver injury — including non-alcoholic fatty liver disease (NAFLD), viral hepatitis, drug-induced liver injury and alcohol-related liver damage. The AST/ALT ratio is particularly useful: a ratio below 1 typically suggests NAFLD, while a ratio above 2 is characteristic of alcoholic liver disease. In Australia, ALT is part of every routine LFT requested by GPs and specialists.
Normal Reference Range
Men: < 40 U/L · Women: < 35 U/L (typical Australian pathology reference range)
Note: Reference ranges may vary between laboratories. Always consult your healthcare provider for interpretation.
Key Facts
- •Category: Vital Organ Functions
- •Unit of Measurement: U/L
- •Test Code: ALT
Related Vital Organ Functions Markers
Albumin
The main protein in blood plasma, produced by the liver.
Learn moreALP (Alkaline Phosphatase)
An enzyme found primarily in the liver and bones.
Learn moreAST (Aspartate Transaminase)
AST (Aspartate Transaminase, also written ASAT or SGOT) is an enzyme found in the liver, heart, skeletal muscle and red blood cells. Because AST exists in multiple tissues, it is less liver-specific than ALT. Pathology labs report AST as part of the standard Liver Function Test (LFT) panel.
Learn moreBilirubin
A yellow pigment produced during the breakdown of red blood cells.
Learn moreBUN (Blood Urea Nitrogen)
A waste product filtered by the kidneys.
Learn moreCreatinine
A waste product produced by muscles and filtered by the kidneys.
Learn more