Ethyl glucuronide in hair detects a high rate of harmful alcohol consumption in presumed non-alcoholic fatty liver disease

Background & Aims: Non-alcoholic fatty liver disease (NAFLD) and alcohol-related liver disease (ALD) cannot reliably be distinguished by routine diagnostics, and the role of alcohol consumption in metabolic dysfunction-associated fatty liver disease (MAFLD) remains unclear. We investigated alcohol con-sumption in patients with presumed NAFLD and ALD using novel objective alcohol markers.Methods: In total, 184 consecutive patients were included in this prospective observational study. Alcohol intake was assessed by ethylglucuronide in hair (hEtG) and urine (uEtG); the utility of these measures for alcohol detection was compared to Alcohol Use Disorders Identification Test-Consumption (AUDIT-C), car-bohydrate deficient transferrin (CDT), mean corpuscular volume (MCV), gamma-glutamyltransferase (GGT), and ALD/NAFLD in-dex (ANI). Clinical characteristics of patients with NAFLD and ALD were re-assessed after reclassification based on repeated moderate (>-10 g <60 g EtOH/day) and excessive (>-60 g EtOH/day) alcohol consumption, and patients were retrospectively reclas-sified based on MAFLD criteria.Results: Repeated moderate to excessive alcohol consumption was detected in 28.6%, 28.5%, and 25.0% of patients with pre-sumed NAFLD, ALD or MAFLD, respectively. ANI score, AUDIT-C, uEtG, and hEtG showed AUCs of 0.628, 0.733, 0.754, and 0.927 for the detection of repeated moderate to excessive alcohol consumption, respectively. The indirect markers CDT, MCV and GGT were not reliable. Patients with repeated moderate or excessive alcohol consumption were significantly more often male, had a significantly lower BMI, and suffered significantly less often from type 2 diabetes or impaired glucose tolerance.Conclusions: In total, 28.6% of patients with presumed NAFLD, and 25.0% with MAFLD are at risk of alcohol-related liver damage. AUDIT-C, uEtG and hEtG should be used to screen for alcohol consumption in patients with fatty liver disease.Lay summary: Fatty liver disease can be caused by metabolic factors and/or alcohol consumption. The diagnosis of non-alcoholic fatty liver disease (NAFLD) is based on the exclusion of harmful alcohol consumption, while metabolic dysfunction -associated fatty liver disease (MAFLD), which has been pro-posed as a new name for NAFLD, is based on the presence of metabolic comorbidities and allows for alcohol consumption. Herein, we show that up to 29% of patients diagnosed with NAFLD and 25% with MAFLD are at risk of alcohol-related liver damage. We show that ethyl glucuronide (a metabolite of alcohol) in the hair and urine can accurately detect potentially harmful alcohol consumption in these patients - as such, these tests should be integrated into routine diagnostic work-up for patients with fatty liver disease.(c) 2022 The Author(s). Published by Elsevier B.V. on behalf of Euro-pean Association for the Study of the Liver. This is an open access article under the CC BY license (http://creativecommons.org/licenses/ by/4.0/).