From the Guidelines
The most effective blood test to indicate alcohol consumption is Phosphatidylethanol (PEth) testing, which is highly specific for alcohol consumption and can detect use for up to 3-4 weeks, as supported by the most recent study in 2025 1. Several blood tests can indicate alcohol consumption, with the most common being liver function tests (LFTs) that measure enzymes like gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). These enzymes become elevated when alcohol damages liver cells. For recent alcohol use, direct alcohol biomarkers include blood alcohol concentration (BAC), which detects alcohol in the bloodstream for about 12-24 hours after consumption, and ethyl glucuronide (EtG) and ethyl sulfate (EtS), which can be detected for up to 3-4 days. For chronic or long-term alcohol use, carbohydrate-deficient transferrin (CDT) is particularly useful as it remains elevated for approximately 2-4 weeks after heavy drinking stops. Mean corpuscular volume (MCV), which measures red blood cell size, can also increase with chronic alcohol use. These tests vary in sensitivity and specificity, with some like PEth and CDT being more specific to alcohol use, while liver enzymes can be elevated due to other conditions affecting the liver. It's essential to consider the limitations and potential confounding factors of each test, as well as the clinical context and patient history, when interpreting the results, as noted in studies from 2020 1 and 2018 1. The use of these biomarkers should be guided by clinical judgment and used in conjunction with other diagnostic tools, such as patient interviews and physical examinations, to provide a comprehensive assessment of alcohol consumption, as recommended by the French Association for the Study of the Liver and the French Alcohol Society clinical guidelines in 2022 1. In clinical practice, a combination of these tests, including PEth, CDT, and LFTs, can be used to screen and monitor alcohol use, as outlined in the position statement by an expert panel on alcohol-related liver disease in 2025 1. Ultimately, the choice of test and interpretation of results should be individualized to each patient's unique circumstances and medical history.
From the Research
Blood Tests for Alcohol Consumption
Several blood tests can indicate alcohol consumption, including:
- Blood alcohol concentration (BAC) 2
- Gamma-glutamyl transferase (GGT) 2, 3, 4, 5
- Carbohydrate-deficient transferrin (CDT) 2, 3, 4, 6, 5
- Alanine aminotransferase (ALT) 2, 6
- Aspartate aminotransferase (AST) 2, 6
- Mean corpuscular volume (MCV) 2, 3, 6
- Phosphatidylethanol (PEth) 2, 6
Sensitivity and Specificity of Blood Tests
The sensitivity and specificity of these blood tests vary, with:
- CDT having a sensitivity of 67% and a specificity of 97% 3
- GGT having a sensitivity of 42% and a specificity of 76% 3
- MCV having a sensitivity of 24% and a specificity of 96% 3
- PEth being a sensitive and specific marker of alcohol consumption, but its application is limited due to the costly equipment necessary for its measurement 2
Emerging Blood Biomarkers
Emerging blood biomarkers for alcohol consumption include: