It is well-established that alcohol has the potential to damage the liver, either from regular chronic use or an occasional binge. When damage to the liver occurs, particular enzymes become elevated in the blood. By measuring these enzymes, we can learn about the extent to which the liver has been damaged, as well as monitor any improvement in liver functioning when patients reduce their alcohol use.
These measures are not diagnostic of an alcohol use disorder, but can be an important part of a comprehensive evaluation.
Due to shame, guilt, stigma, and/or poor recall, a patient’s self-report of alcohol use is notoriously inaccurate. This 2007 study revealed a low correlation between biomarker test results and self-reported alcohol use. For understandable reasons, people tend to under-report their alcohol use.
It is not uncommon for patients to find additional motivation to change their drinking patterns based on elevated liver enzymes. Regular GGT testing, for example, has been associated with lower rates of alcohol use, fewer missed days of work related to alcohol use, and improved liver functioning.
Indirect Laboratory Markers
GGT (Gamma Glutamyl Transferase): This is the most commonly used biomarker for liver damage caused by alcohol consumption. GGT becomes elevated from about 4 daily drinks over a period of several weeks. The results are most accurate for those between 30 and 60 years old.
AST (Aspartate Amino Transferase): It reflects general liver damage that is often, but not necessarily, related to alcohol use. However, AST is also found in other organs, such as the brain, heart, kidney, and muscle, so it is not a very specific measure of liver damage.
ALT (Alanine Amino Transferase): Less sensitive than AST.
MCV (Mean Corpuscular Volume): This refers to the size of your Red Blood Cells (RBC). The way that alcohol causes the size of RBCs is still unknown. However, alcohol appears to directly disrupt RBC development. The RBCs return to their normal size, after several months without drinking alcohol.