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Markers of Recent Drinking

Certain tests can show if a person has been recently drinking alcohol, even when no ethanol can be detected in his or her body ^[1]:

Chart 1. Markers of Recent Drinking
TEST	Minimal alcohol amount needed for a positive test	The time after stopping drinking during which the test is positive	Causes of false positive results	Causes of false negative results
Carbohydrate-deficient transferrin (CDT) [blood]	4-6 drinks/day for 1-3 weeks	2-4 weeks	Iron deficiency, advanced liver cirrhosis, liver cancer, carbohydrate-deficient glycoprotein syndrome, genetic D variants of transferrin, antiepileptics.	30-40% false negatives despite heavy drinking ^[2]. Oral contraceptives, angiotensin II receptor blockers (losartan, valsartan) may decrease CDT levels.
Gamma-glutamyltransferase (GGT) [blood]	4-6 drinks/day for several weeks	1-4 weeks	Smoking, obesity, pancreatitis, prostate, renal or liver disease, hypertriglyceridemia, diabetes, phenytoin, NSAIDs, oral contraceptives, barbiturates, venlafaxine, anticoagulants	20-60% false negatives despite heavy drinking ^[2]
Ethyl glucuronide (EtG) [urine]	a single drink or even 1 gram alcohol	2 hours – 5 days	Alcohol-containing foods and medicines, non-alcoholic beer, vapors of alcohol beverages and volatile ethanol-containing liquids and aerosols, kidney disease, technical errors.	10-30% false negatives despite regular drinking ^[2]. Drinking water before the test, urinary tract infection and technical errors may reduce urine EtG levels.
Ethyl glucuronide (EtG) [hair]	4 drinks/day	3 months	EtG-containing hair cosmetics (rare) ^[3]	6% false negative results despite heavy drinking ^[4]. Regular hair hygiene over the months and hair bleaching may wash out EtG from the hair ^[5,6]

Chart 1 source: Niaaa.nih.gov ^[1]

Carbohydrate-Deficient Transferrin (CDT)

Carbohydrate-deficient transferrin (CDT) in the blood is elevated in 60-70% individuals after 1-3 weeks of drinking 4-6 drinks (50-80 g alcohol) per day ^[2]. CDT levels return to normal within 2-4 weeks of abstinence ^[7]. After stopping drinking, 30% decrease in CDT level means abstinence, and 30% increase after 3 weeks of abstinence means relapse ^[7].

False positive results may be due to iron deficiency, advanced liver cirrhosis, liver cancer, carbohydrate-deficient glycoprotein syndrome, genetic D variants of transferrin or use of enzyme-inducing antiepileptic drugs. False negative results may be due to use of oral contraceptives or angiotensin II receptor blockers (losartan, valsartan) ^[7].

Gamma-Glutamyl Transferase

The liver enzyme gamma-glutamyl transferase (GGT) in the blood is elevated in 40-80% individuals who have been drinking at least 4-6 drinks (60-80 g alcohol) per day continually for several weeks ^[2,7]. GGT levels return to normal within 1-4 weeks of abstinence ^[7].

GGT levels are increased with smoking, pancreatitis, prostate or renal disease, liver disease, bile duct obstruction, hypertriglyceridemia, diabetes, obesity, and the use of phenytoin, NSAIDs, oral contraceptives, barbiturates, venlafaxine, or anticoagulants ^[2,7].

In individuals before 30 and after 60 years, the results may be unreliable ^[7].

Peterson K, 2004, Biomarkers of alcohol use and abuse National Institute on Alcohol Abuse and Alcoholism
Tavakoli HR et al, 2011, Review of Current Clinical Biomarkers for the Detection of Alcohol Dependence PubMed Central
Sporkert F et al, 2012, Positive EtG findings in hair as a result of a cosmetic treatment PubMed
Høiseth G et al, 2009, Ethyl glucuronide in hair compared with traditional alcohol biomarkers–a pilot study of heavy drinkers referred to an alcohol detoxification unit PubMed
Tsanaclis L, 2009, Testing for alcohol use in hair: is ethyl glucuronide (EtG) stable in hair? Annales de Toxicologie Analytique
Morini L et al, 2010, Effect of bleaching on ethyl glucuronide in hair: an in vitro experiment PubMed
Kalapatapu RK et al, 2009, Novel Objective Biomarkers of Alcohol Use: Potential Diagnostic and Treatment Management Tools in Dual Diagnosis Care PubMed Central