Duration of abstinence before blood test, alcohol consumption and age was examined in 177 male alcohol-dependent patients as factors influencing serum carbohydrate-deficient transferrin (CDT), serum γ-glutamyltransferase (GGT) and mean corpuscular volume (MCV). The strongest influence on all markers was the factor 'duration of abstinence before blood test'. In patients who had been abstinent for >4 days before the blood test, the markers had low sensitivities (GGT, 33%; CDT, 14%; MCV, 42%),

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... eas in patients with ≤ 4 days of abstinence the markers had reasonably good sensitivities (GGT, 72%; CDT, 56%; MCV, 48%). GGT was more sensitive than CDT (P < 0.05) and MCV (P < 0.001). The combined use of CDT and GGT had sensitivity of over 90%. Mean alcohol consumption in the 30 days prior to the blood test had a significant effect on CDT and GGT, but not on MCV. Age did not have a clear effect on CDT and GGT. For MCV, a significant and linear increase with age was shown. We conclude that GGT is the most sensitive of these three markers. Using GGT and CDT combined, sensitivity can be enhanced to over 90%. The period of abstinence before the blood test has a strong influence on CDT and GGT. If a longer period of abstinence is suspected, MCV should also be measured, in order to detect evidence of earlier heavy drinking.