How are indirect alcohol biomarkers used to detect the toxic effects of alcohol?

Updated: Nov 27, 2018
  • Author: Warren Thompson, MD, FACP; Chief Editor: Glen L Xiong, MD  more...
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Answer

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, 40, 6] (See Table 2 below.) CDT is less sensitive/specific in women than men. [41]

  • 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, 40] 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. [42]

  • 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). [40, 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]

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. [40, 6, 41, 43, 44]

† The sensitivity comes from one study in Finland, which uses a special formula. This study needs to be replicated. [45]


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