Effect of combined substance use on laboratory markers of alcoholism.

This article examines the commonly used laboratory indicators of heavy alcohol use (elevated MCV, GGTP and AST values) in subgroups of drug-using and non-drug-using alcoholic men admitted to an inpatient alcoholism treatment program. A total of 380 consecutive admissions meeting DSM-III diagnostic criteria for alcohol use or dependence were studied. Of these subjects, 75% used both alcohol and drugs. The most frequently used drugs were marijuana, cocaine, amphetamines and tranquilizers. Overall, subjects who used drugs with alcohol had significantly lower MCV and GGTP values than subjects who used alcohol alone. More specifically, cocaine use was associated with lower MCV values, marijuana use with lower AST values and heroin use with higher AST and GGTP values. These differences between drug-using and non-drug-using alcoholics were significant even after controlling for variables that affect the laboratory values such as age, quantity, frequency and duration of alcohol consumption. These findings indicate that any study of laboratory markers of alcoholism needs to consider concomitant illicit drug use patterns.