Alcoholism Workup

Updated: Sep 12, 2017
  • Author: Warren Thompson, MD, FACP; Chief Editor: Randon S Welton, MD  more...
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Workup

Laboratory Studies

Biomarkers

Alcohol biomarkers are physiological indicators of alcohol exposure or ingestion and may reflect the presence of an alcohol use disorder. These biomarkers are not meant to be a substitute for a comprehensive history and physical examination by an appropriate health professional. Instead, alcohol biomarkers should be a complement to self-reported measures of drinking. [4]

In a population of psychiatric patients, research evidence has shown the usefulness of biological measures in the detection of alcohol use disorders when compared with patient self-report. A 2007 study of 486 consecutively admitted psychiatric patients showed a low correlation between self-reported consumption of alcohol and illicit drugs and biological measures; 52% of the patients underreported their consumption of illicit drugs when compared with urine toxicology screening results; 56% of patients underreported alcohol use as evaluated by carbohydrate-deficient transferrin (CDT), and 37% of patients underreported alcohol use as evaluated by CDT + gamma glutamyltransferase (GGT). [40] Replication of such research in a primary care population is needed to show that biological measures aid the primary care clinician in detecting alcohol use disorders.

Alcohol biomarkers are generally divided into indirect and direct biomarkers. [4]

Indirect alcohol biomarkers suggest heavy alcohol use by detecting the toxic effects that alcohol may have had on organ systems or body chemistry. [4]

  • Indirect alcohol biomarkers include aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyltransferase (GGT), mean corpuscular volume (MCV), and carbohydrate-deficient transferrin (CDT). [4]
  • GGT, AST, and MCV are the most frequently used indirect biomarkers. [5] As a screen for alcohol dependence, the sensitivity/specificity of CDT is generally higher than AST, ALT, GGT, or MCV. [4, 41, 6] (See Table 2 below.) CDT is less sensitive/specific in women than men. [42]
  • CDT is a collection of various isoforms of the iron transport protein transferrin. [5] Alcohol consumption above 50-80 g/d for 2-3 weeks appears to increase serum concentrations of CDT. [6, 41] CDT tends to distinguish chronic heavy drinkers from light social drinkers. [5] A number of different ways are available to measure CDT; some may be better than others, depending on factors such as the type of alcohol consumption and gender. [43]
  • The combination of GGT and CDT compared with GGT or CDT alone shows a higher diagnostic sensitivity, a higher diagnostic specificity, and a stronger correlation with the actual amounts of alcohol consumption (see Table 2 below). [41, 6] Combination GGT/CDT values appear to increase after the daily alcohol consumption exceeds a threshold of 40 g. [6] This approach is cost-effective, easy to manage in hospital laboratories, and should be suitable for routine clinical care. [6]
  • Other indirect alcohol biomarkers of emerging interest include total serum sialic acid (TSA), 5-hydroxytryptophol (5-HTOL), N-acetyl-beta-hexosaminidase (Beta-Hex), plasma sialic acid index of apolipoprotein J (SIJ), and salsolinol. [7]

Direct alcohol biomarkers are analytes of alcohol metabolism. [4]

  • Direct alcohol biomarkers include alcohol itself and ethyl glucuronide (EtG). [4]
  • A blood alcohol level might be helpful in the office if the patient appears intoxicated but is denying alcohol abuse. A blood alcohol level in excess of 300 mg/dL, a blood alcohol level of greater than 150 mg/dL without gross evidence of intoxication, or a blood alcohol level of greater than 100 mg/dL upon routine examination indicates alcoholism with a high degree of reliability. The short half-life of alcohol limits its use widely as a biomarker. [6] As the blood alcohol level detects alcohol intake in the previous few hours, it is not necessarily a good indicator of chronic excessive drinking. [5]
  • EtG is a minor, nonoxidative, water-soluble, stable, and direct metabolite of alcohol that is formed by the conjugation of ethanol with activated glucoronic acid. [41, 6, 5] Shortly after alcohol intake, even in small amounts, EtG becomes positive. [5] After complete cessation of alcohol intake, EtG can be detected in urine for up to 5 days after heavy binge drinking [7, 6] , making EtG an important biomarker of recent alcohol consumption. [5] A 2006 report by the Substance Abuse and Mental Health Services Administration states that the use of EtG should be considered as a potential valuable clinical tool, but the use of EtG in forensic settings is premature. [4]
  • Other direct alcohol biomarkers of emerging interest include acetaldehyde, fatty acid ethyl esters (FAEE), Ethyl Sulfate (EtS), and Phosphatidylethanol (PEth). [4, 7]

Table 2. Sensitivity and Specificity of Alcohol Biomarkers* (Open Table in a new window)

Biomarker Sensitivity (%) Specificity (%)
AST 15-69 47-68
ALT 18-58 50-57
GGT 34-85 11-95
MCV 34-89 26-95
CDT 39-94 82-100
CDT + GGT 90 † 98
Alcohol 0-100 0-100
EtG 76-91 77-92
*Values vary considerably according to gender, age, drinking pattern, prevalence of alcohol abuse/dependence, and prevalence of comorbidity, among other factors. [41, 6, 42, 44, 45]



† The sensitivity comes from one study in Finland, which uses a special formula. This study needs to be replicated. [46]



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Other Tests

The possibility of polysubstance abuse/dependence justifies performing a blood/urine toxicology screen for other substances of abuse.

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