What is AST?

Aspartate aminotransferase (AST) is an enzyme found in high concentrations in the liver, heart, muscles, and kidneys. When these organs are damaged, AST is released into the bloodstream.

Why is it Important?

AST is used to:

Detect liver damage or disease
Monitor liver disease progression
Assess heart muscle damage
Evaluate muscle disorders
Assess effectiveness of liver treatments

AST is often measured alongside ALT (another liver enzyme) to determine the AST/ALT ratio.

Normal Ranges

Group	Range	Unit
Men	10 – 40	U/L
Women	9 – 32	U/L

What Do Abnormal Results Mean?

High AST

Common causes include:

Liver disease (hepatitis, cirrhosis, fatty liver)
Heart attack (myocardial infarction)
Muscle injury or disease
Alcohol abuse
Medications (statins, antibiotics, chemotherapy)
Hemolysis (red blood cell breakdown)

AST/ALT Ratio

The ratio helps identify specific conditions:

Ratio > 2: Alcoholic liver disease
Ratio < 1: Non-alcoholic fatty liver disease, viral hepatitis
Ratio ~ 1: Acute liver damage

Low AST

Low AST is rare and generally not clinically significant. Can occur with:

Vitamin B6 deficiency
Uremia (kidney failure)

When Should You Get Tested?

AST is part of routine liver function tests and comprehensive metabolic panels. Your doctor may order it if you have symptoms like jaundice, abdominal pain, nausea, fatigue, or risk factors for liver disease.