Alcohol abuse is a major cause of liver disease. While ethanol itself has been shown to be hepatotoxic, its primary metabolite acetaldehyde has also been implicated in the pathogenesis of alcoholic liver disease. The majority of ethanol metabolism occurs in the liver and high concentrations of acetaldehyde accumulate during chronic ethanol abuse. Acetaldehyde has been shown to react with many proteins in vitro, forming stable covalent adducts. These modifications can act as neoantigens and may also alter biological function. Acetaldehyde-modified proteins have been detected in the livers of ethanolfed rats and human alcoholics. Circulating antibodies reactive with modified proteins have also been detected. A direct linkage between acetaldehyde-modified proteins, antibodies and liver damage has yet to be established, but current research should clarify the picture in the next few years.

Carbohydrate-deficient transferrin (CDT) has emerged as the best new marker for alcohol abuse. Recently plasma immunoglobulin A (IgA) reactivity with acetaldehyde (AcH)-modified proteins, or the modified proteins per se, have been proposed as a markers for high levels of alcohol consumption. In this study, we have compared CDT, IgA reactivity with AcH adducts (IgA ASR), and AcH-modified albumin with conventional markers of high alcohol intake in groups with well-defined drinking histories. The plasma activity of ALT, AST, and gamma-glutamyltransferase increased steadily with increasing alcohol consumption. CDT and AcH-modified albumin showed a similar pattern, whereas IgA ASR appeared only to be elevated after a threshold level of consumption had been reached. Neither CDT IgA ASR or AcH-modified albumin correlated strongly with any of the conventional markers or each other. This study shows that CDT, IgA ASR, AcH-modified albumin, and the conventional markers are not related, but suggests that the concurrent use of CDT and IgA ASR may lead to better identification of high alcohol intake.

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