This page helps you to understand blood test results for your ALT and gives you the reference range to determine if your lab test results mean that you a have high, low or normal ALT levels.
We outline the risk factors associated with raised and low ALT levels.
Reference Ranges for ALT:
|US Conventional Units||U/L||<=41||>=42|
|Standard International Units||U/L||<=41||>=42|
What is Alanine transaminase (ALT)
ALT is an enzyme found mostly in the cells of the liver and kidney. When the liver is damaged, ALT is released into the blood. This makes ALT a useful test for early detection of liver damage.
ALT and Aspartate transaminase (AST) are considered to be two of the most important tests to detect liver injury, although ALT is more specific to the liver than AST. Sometimes ALT is compared directly to AST and an AST/ALT ratio is calculated. This ratio may be used to distinguish between different causes of liver damage and to help recognize heart or muscle injury.
Function of Alanine transaminase (ALT)
ALT is used to help your body to metabolize protein.
Risk factors associated with Alanine transaminase (ALT)
In infectious hepatitis and other inflammatory conditions affecting the liver, ALT is characteristically as high as or higher than AST, and the ALT/AST ratio, which is normally <1, increases. ALT levels are usually elevated before clinical signs and symptoms of disease appear. Elevated ALT values are seen in parenchymal liver diseases characterized by a destruction of hepatocytes, where values are typically at least ten times above the normal range. Levels may reach values as high as one hundred times the upper reference limit, although twenty to fifty-fold elevations are most frequently encountered .
Notable variations by Demographic Group
A 2013 study on ALT in the US population showed that there was considerable demographic variation in the proportion of the total U.S. population with elevated ALT. ALT elevation was more prevalent among Mexican-Americans and less prevalent among African Americans. ALT elevation was more common among young and middle-aged men, but peaked in middle age among women. The prevalence of ALT elevation increased with increasing BMI .