The AST and ALT levels on your blood test results – what do they mean?
AST and ALT are two common markers for diagnosing liver diseases. Patients with liver disorders often find their AST and ALT levels unsatisfactory, but what do the figures actually imply? And do patients of every kind of liver dysfunctions have the same levels?
Although the normal range of AST and ALT level varies among laboratories and countries, the ratio of AST:ALT is key when it comes to diagnosing liver diseases. The use of this ratio was first suggested by de Ritis in 1955. He found that the ratio decreased in patients with acute viral hepatitis and increased in patients with cirrhosis.
The AST:ALT ratio in a healthy individual would be around 1.15. If the ratio is more than 2.0 (up to 6.0), this denotes alcoholic liver disease. And if the ratio is between 1.4 and 2.0, it suggests cirrhosis. Interestingly enough, the severity of cirrhosis is measured by the level of the ratio, implying that patients of cirrhosis with a high AST:ALT ratio would probably have a more advanced case of cirrhosis. On the other hand, patients with acute viral hepatitis often have a very low AST:ALT ratio, ranging from 0.5 to 0.8.
Since AST level will increase significantly after one consumes alcohol, it could also be a marker for alcohol consumption. However, it should be noted that most patients with high alcohol consumption but without severe liver disease often do not have an AST/ALT ratio above 1, which means that a high ratio could probably be a result of advanced alcoholic liver disease.
Here’s an easy way to find out your AST:ALT ratio: divide your AST level as shown on your blood test results by your ALT level. For example, if your AST is 20 U/L and your ALT is 18 U/L, then your ALT ratio would be 1.05, which is within the normal range.
What is the magnitude of AST and ALT elevations for acute viral hepatitis?
Not only is the AST:ALT ratio useful when it comes to diagnosing liver diseases, the magnitude of AST and ALT elevations is also a crucial marker when it comes to differentiating the type of liver diseases patients have. One of the most obvious diseases that can be diagnosed through this method is acute viral hepatitis. In a research study of 15 laboratory tests, it was shown that all acute viral hepatitis patients showed an AST level greater than 200 U/L and an ALT level greater than 300 U/L, which both are 25 times the upper limit of normal levels.
Are AST and ALT elevations always related to liver diseases?
Since AST is found in various organs like liver, kidneys, heart, skeletal muscles, and brain, elevation of AST level could also be related to acute cardiac or skeletal muscle injury. A lesser degree of ALT elevation could also signal skeletal muscle injury or it is simply a bodily reaction after vigorous exercise. Therefore, AST and ALT elevations do not always suggest hepatic conditions, even though care should still be given when such situations occur.
Despite the wide range of causes for AST and ALT elevations, it should never be ignored or viewed as a temporary issue. Since the increased levels of AST and ALT suggest the liver is inflamed, patients could try ways to lower the levels by first stopping any form of alcohol intake, followed by doing regular exercises and maintaining a balanced diet with sufficient portions of whole grains, leafy green vegetables, and dairy products. If necessary, patients could always try taking liver supplements that are safe and proven to help lower both the AST and ALT levels. Once both levels are controlled, it is a good indication that the liver is no longer inflamed or damaged.
- ResearchGate, https://www.researchgate.net/publication/20469142_Aminotransferase_in_disease?_sg=0nEdOpjU5caeZqIwRHi2c2Cs3SLERoLY7nZjZ9e7ufoym2kU6g5s3ASTsstvw0bvwWqqUbs5Pg, (Access Date: 2018-07-03)
- Oxford Academic, https://academic.oup.com/alcalc/article/39/4/336/139692, (Access Date: 2018-07-03)
- Cleveland Clinic Center for Continuing Education, http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/hepatology/guide-to-common-liver-tests/, (Access Date: 2018-07-03)
- Family Practice News, https://www.mdedge.com/familypracticenews/article/103462/infectious-diseases/high-alt/ast-ratio-linked-fatty-liver-risk-hcv, (Access Date: 2018-07-03)
- * All research and clinical data should be used as reference purposes only, results may vary.