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Alanine Transaminase Blood Test

Last updated Nov. 18, 2018

Approved by: Krish Tangella MD, MBA, FCAP

Alanine Transaminase Blood Test is mainly used to diagnose or monitor liver damage and is often ordered along with AST (aspartate transaminase, another enzyme found in liver and heart cells), or as part of a liver panel.

What are the other Names for this Test? (Equivalent Terms)

  • Alanine Aminotransferase Blood Test
  • Glutamic-Pyruvic Transaminase (GPT) Blood Test
  • Serum Glutamic-Pyruvic Transaminase (SGPT) Blood Test

What is Alanine Transaminase Blood Test? (Background Information)

  • Alanine transaminase (ALT) is an enzyme found in liver and kidney cells. It also occurs in lower quantities in heart and muscle cells
  • While the normal blood levels of ALT are low, any damage to the liver cells releases the enzyme into the blood stream. Consequently, increased levels are detected on testing
  • Alanine Transaminase Blood Test is mainly used to diagnose or monitor liver damage and is often ordered along with AST (aspartate transaminase, another enzyme found in liver and heart cells), or as part of a liver panel
  • ALT is more specific for the liver. Often, the blood levels of ALT rise, even before obvious signs and symptoms of liver damage appear
  • An AST/ALT ratio also helps in ascertaining the probable cause of liver damage and to differentiate between liver damage and damage to the heart or muscles

What are the Clinical Indications for performing the Alanine Transaminase Blood Test?

Indications for Alanine Transaminase Blood Tests include:

Symptoms and signs of liver disease, such as:

  • Abdominal pain, abdominal swelling
  • Nausea, vomiting
  • Jaundice
  • Dark-colored urine
  • Pale stools
  • Itching
  • Easy bruising

To assess individuals at increased risk of developing liver disease, such as:

  • Heavy drinkers
  • Those with a family history of liver disease
  • Individuals with known/probable history of hepatitis exposure
  • Overweight individuals

Monitoring individuals on drugs known to be toxic to the liver, or in monitoring individuals with known liver disease.

How is the Specimen Collected for Alanine Transaminase Blood Test?

Sample required: Blood

Process: Blood sample is drawn through a needle inserted into the vein (arm).

Preparation required: None

What is the Significance of the Alanine Transaminase Blood Test Result?

The normal blood levels of Alanine Transaminase, called the reference range for ALT, may vary slightly from lab to lab. Hence, most lab reports come with a reference range, which is used in that particular centre. A physician interprets the results based on the reference values provided.

A standard reference range in wide use is 10-40 IU/L (international units per liter).

ALT levels are increased in liver disease; some of the causes of which include:

  • Hepatitis (acute hepatitis causes much higher values, as compared to chronic hepatitis)
  • Cirrhosis of the liver (formation of scar tissue in the liver), due to a variety of causes
  • Hemochromatosis (liver damage results from accumulation of too much iron)
  • Liver cancers
  • Taking drugs toxic to the liver
  • Decreased blood flow to the liver
  • Bile duct obstruction
  • Heart damage and pancreatitis may also cause increase in ALT levels

While ALT levels are usually elevated more than AST (aspartate transaminase) in liver disease, leading to an AST/ALT ratio < 1, some conditions like alcoholic hepatitis, cirrhosis, and heart/muscle damage, may cause an increased AST/ALT ratio > 1.

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • Alanine transaminase levels may also be increased following strenuous exercise

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Feb. 23, 2014
Last updated: Nov. 18, 2018