I. What Is Alanine Aminotransferase Testing?

ALT testing is one of the most commonly used tests for detecting liver disease, which can lead to scarring and liver failure if left untreated. The death rate for chronic liver disease jumped 31% among Americans aged 45 to 64 years over a 15-year period.

Why should you get tested

Early diagnosis and treatment of liver damage can help improve outcomes. ALT testing can detect the presence of cirrhosis, hepatitis, and other liver diseases before symptoms even appear.

Who should get tested

Your doctor may order an ALT test if you show signs of liver disease or are at increased risk because of family history, alcohol and drug consumption, or exposure to hepatitis viruses. The test is commonly included as part of routine health exams, including comprehensive metabolic panels.

When to get tested

If you have symptoms of liver disease such as jaundice, dark urine, nausea, vomiting, and pain in the upper right abdomen, ask your doctor about measuring your ALT levels. ALT testing is also used to monitor improvement during the treatment of liver disease.

II. How to Prepare for Alanine Aminotransferase Testing

An ALT test doesn’t require special preparation. If the test is performed with other screenings, such as a comprehensive metabolic panel, you may need to fast prior to testing.

III. How an Alanine Aminotransferase Test Works

Alanine aminotransferase is an enzyme the liver uses to help convert food into energy. ALT levels are normally low in people with healthy livers, but damaged liver cells result in leakage of the enzymes and elevated ALT levels.

By measuring ALT levels in your blood, this test can usually tell if your liver is inflamed or damaged.

ALT testing is performed with a sample of blood drawn in a laboratory. A technician uses a small needle to collect blood from a vein, usually in your arm.

You can also test at home by purchasing a kit online. The kits come with supplies to collect your sample and send it to a lab for analysis. ALT tests are usually included as part of liver panel home test kits.

IV. Understanding Alanine Aminotransferase Testing Results

ALT test results are usually sent to your doctor or are available online within a week. The results indicate the level of ALT measured in your body, in units per litre, or IU/L.

A person with a healthy liver usually has ALT levels of 40 IU/L or less.

Your results should be reviewed with a medical professional. As a general rule, ALT levels:

  • Of more than 500 IU/L are considered high and can indicate acute hepatitis caused by a viral infection or toxins
  • Between 300 and 500 IU/L are considered moderate and may indicate chronic hepatitis
  • Between 40 IU/L and 300 IU/L are considered mild elevations, and can be caused by conditions such as non-alcoholic fatty liver disease and alcohol-related liver disease

Several conditions can cause increased ALT levels, so your doctor may need to compare your ALT measurements with levels of other enzymes, such as aspartate aminotransferase (AST) for an accurate diagnosis. If your ALT test wasn’t performed as part of a liver panel, additional tests might be required.

V. Learn From Our Alanine Aminotransferase Sources

We consulted a variety of sources to create this overview of ALT testing. For more information about liver testing and liver disease, please refer to these websites.