Available markers of excessive alcohol use.

The need for objective diagnostic tools in people with alcohol intake abuse is one of the major needs in daily clinical practice. Determination of blood alcohol concentration is commonly used in cases of suspected acute alcohol intoxication, especially in the emergency room. A dose-dependent correlation between alcohol consumption and mean corpuscular volume (MCV) is a known index of excessive alcohol intake. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels are frequently elevated (2-4 times above normal) in patients with alcohol use disorder and an AST/ALT ratio >2 is indicative of alcohol-related liver disease. Several studies highlighted a positive correlation between alcohol consumption and serum gamma-glutamyl transferase (γGT) levels, with increased values in about 75% of patients drinking >60 g/day of ethanol for at least 5 weeks. Also, 60-80 g of alcohol per day for a minimum of 2 weeks can result in increased carbohydrate-deficient transferrin (CDT) levels (normally less than 2% of total transferrin). Complete abstinence from alcohol leads to a normalization of CDT values in approximately 2-3 weeks. Ethyl glucuronide (EtG) is detectable in urine from a minimum of 6 hours up to a maximum of 100 hours after alcohol intake. In-vitro studies showed that the levels of phosphatidylethanol (PEth) in human red blood cells were proportional to ethanol concentration and exposure time, suggesting an important role in differentiating abstinence from unhealthy drinking. γGT and CDT are the most useful markers for monitoring chronic alcohol abstinence, whereas blood alcohol concentration and urinary EtG are the most valuable indexes of acute alcohol consumption. In conclusion, no specific laboratory marker alone is reliable to identify patients with alcohol abuse, thus the best diagnostic strategy includes combined index use in addition to other screening tools (i.e., clinical history/context and questionnaires).