Classical biomarkers in alcohol screening: CDT, MCV and liver enzymes combined with AUDIT versions - results from the 2026 German S3 Guideline Alcohol

Kurzzusammenfassung in leicht verständlicher Sprache

Classical alcohol biomarkers such as GGT, AST/ALT, MCV and CDT are useful in clinical practice, but they should not be used alone to diagnose alcohol-related disorders. The German S3 Guideline recommends AUDIT or AUDIT-C as the first screening step. Biomarkers are most helpful when self-report is uncertain, chronic heavy drinking is suspected, or monitoring is needed. Combining markers, especially GGT with CDT or MCV, can improve diagnostic accuracy. In practice, biomarkers should complement structured history-taking, clinical assessment and, when needed, direct markers such as PEth or EtG.

Abstract

Hintergrund und Fragestellung
Classical indirect alcohol markers—gamma-glutamyltransferase (GGT), aspartate/alanine aminotransferases (AST/ALT), mean corpuscular volume (MCV) and carbohydrate-deficient transferrin (CDT)—are widely available but often overinterpreted. The 2026 update of the German evidence- and consensus-based S3 guideline clarifies their role alongside AUDIT-based screening.

Methoden
This presentation summarises guideline recommendations derived from adapted source guidelines and systematic evidence updates on biomarkers, AUDIT/AUDIT-C and combined diagnostic approaches, with emphasis on applicability in primary care, emergency, psychiatric and inpatient settings.

Ergebnisse
AUDIT remains the best-established questionnaire for risky alcohol use and alcohol-related disorders; AUDIT-C is recommended when time is limited. A German cut-off of five points, with possible reduction to four in women, is supported for AUDIT/AUDIT-C screening. Classical markers should not be used as isolated diagnostic tests. GGT is sensitive but non-specific, AST/ALT indicate hepatocellular injury, MCV changes slowly and has multiple differential diagnoses, while CDT offers higher specificity for sustained heavy drinking but variable sensitivity. For chronic use, combinations such as GGT+CDT, GGT+MCV+CDT, gamma-CDT/Antilla index or Alc index can increase diagnostic accuracy and are recommended for screening/monitoring when chronic heavy alcohol consumption is the clinical question. Evidence does not support a formal algorithm combining AUDIT with indirect markers, but pragmatic sequential use is recommended: AUDIT/AUDIT-C first, followed by marker combinations when self-report is inconsistent, monitoring is required or organ findings raise suspicion.

Diskussion und Schlussfolgerung
In practice, classical biomarkers are complementary tools, not substitutes for structured history and ICD-based diagnosis. Their best use is targeted, contextualised and combined with AUDIT-based screening, differential diagnosis and, where necessary, direct markers such as PEth or EtG.

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Ich bzw. die Koautorinnen und Koautoren erklären, dass während der letzten 3 Jahre die folgenden wirtschaftlichen Vorteile oder persönlichen Verbindungen bestanden: