What is ALT?
Liver Health

What is ALT?

Written by

Lauren Dobischok
16 May, 2022

Medically checked article All HOMED-IQ content is reviewed by medical specialists

Alanine aminotransferase (ALT) is an enzyme found primarily in liver cells, and to a lesser extent in other cells of the body. When the liver is damaged or inflamed, excess ALT can leak into the bloodstream. Therefore, testing ALT can give you insight into the functioning of your liver. Homed-IQ offers a home test for ALT and other key liver enzymes to test the health of your liver. In addition to ALT, this test also analyzes other values, such as AST, Gamma GT, Alkaline Phosphatase, and bilirubin.

What is ALT?

ALT is a liver enzyme. As a protein, ALT ensures that certain substances are converted into other substances. When the liver is damaged or inflamed, ALT can leak out of the liver and end up in the blood. Even minor damage to the liver can cause slightly elevated ALT levels. The liver has many important functions, including removing toxic substances from the blood. The liver also ensures absorption of vitamin D and vitamin K, as fat-soluble vitamins.

What are normal ALT values?

To determine whether you have a healthy ALT level, it is important to know what the reference values are. According to the standard of NHG (Nederlands Huisartsen Genootschap) a different reference value applies for men and women:

ALT value for men: < 45 U/L

ALT value for women: < 34 U/L

What does elevated ALT mean?

ALT may be elevated if liver damage has occurred. However, a slightly elevated ALT level usually has no meaning. The higher the value, the greater the chance that serious damage has occurred. A rule of thumb for ALT is that the value should not be more than three times the applicable upper limit to be considered healthy.

What ALT level is harmful?

ALT can potentially be harmful when it exceeds the reference value. However, there is a difference in the degree of harmfulness. An extremely high value of 2,000 ALT, for example, means that the liver is functioning very poorly and even so badly that acute intervention is necessary. An ALT value of 400 is also a harmful value, but it is still possible to reduce the value with limited long-term effects. At a value of 1,000 ALT, liver cells die.

ALT Testing

If you want to know what the performance of your liver is, it is possible to test the value of ALT. This gives an objective picture of your liver’s function and can be important to uncovering a liver condition because symptoms are not always present in liver disease. Homed-IQ has a home test available that allows users to determine their ALT value, along with several other key liver enzymes. The test involves taking a blood sample using a finger prick. This sample is then analyzed by a certified laboratory. Homed-IQ’s Liver Function Blood Test also evaluates the following biomarkers:

With the Liver and Kidney Function Test, you can also analyses important markers for your kidney health.

What is the difference between ALT and AST?

ALT and AST are both liver enzymes, but they are different from each other in several ways. The production of ALT takes place in the main type of liver cells (hepatocytes). The level of ALT in the blood rises when these liver cells are damaged or have died.

AST (Aspartate Aminotransferase) is similar to ALT, but it is not entirely aimed at indicating liver disease. This is because the production of ASAT also takes place in muscle cells in the body. If there is liver disease as a result of excessive alcohol consumption, AST is often higher than ALT.

What are the causes of an elevated ALT value?

There are various causes that can lead to elevated ALT. An example of this is acute hepatitis (inflammation of the liver), where the value can be ten to fifteen times higher than the reference value. Another important cause of ALT that is too high is chronic alcohol abuse (Jellinek, 2014), fat accumulation in the liver (fatty liver) and extreme obesity due to an unhealthy lifestyle.

Are there any diseases related to elevated ALT?

There are several diseases related to elevated ALT, such as:

  • Acute viral hepatitis infection
  • Liver cancer
  • Cirrhosis of the liver
  • Chronic liver inflammation
  • Blockage of the bile ducts

There is a reason that when liver function is tested not only the value of ALT, but also AST is measured. For example, in diseases such as liver cirrhosis, ALT may be only slightly or not elevated at all. It is not possible to deduce from this value alone what the liver’s health is. That is why liver testing is not just for ALT, but also for other biomarkers like AST and Alkaline Phosphatase (AF) (Maag Lever Darm Stichting, 2013).

What are the consequences of an ALT value that is too high?

The health impacts of high ALT depend on the magnitude of the ALT value and its cause. In end-stage liver cirrhosis, there is nothing more that can be done to save the liver, but with slightly to moderately elevated ALT it is possible to get the level down through medical intervention and/or lifestyle changes. In any case, if ALT is too high the liver will not function optimally and follow-up care with a doctor is needed.

What should I do if I have an elevated ALT value?

There are several lifestyle changes that can help lower ALT, such as by stopping drinking alcohol. It is also good to drink a few cups of coffee a day, because coffee has a positive effect on lowering ALT. It is also recommended to limit the intake of sugar and unhealthy fats and eat more vegetables, fruit, and fiber-rich foods. If you are overweight, it is important to lose weight in order to help reduce your ALT. Furthermore, it is of course recommended to maintain a healthy lifestyle in general. That also means making sure you get enough exercise. Additionally, there are also medical treatments available for certain liver diseases, such as for acute hepatitis.

About the author

Lauren Dobischok

Lauren is a health scientist and science communicator currently living in the Netherlands. Originally from Canada, she completed a Research Master’s in Health Sciences at the Netherlands Institute of Health Sciences at Erasmus University Rotterdam (NIHES) with a specialisation in epidemiology. Prior to her master’s degree, she completed a Bachelor’s degree in Health Sciences at Simon Fraser University. With a background in public health, her goal is to create accurate scientific content that is easy to understand and empowers people to make informed decisions. Within Homed-IQ, Lauren works as a Product Developer and Content Lead, working closely with physicians and scientists on medical devices for Homed-IQ’s new products and written communications.