Ethyl glucuronide in keratinous matrices as biomarker of alcohol use: A correlation study between hair and nails

Abstract

To quantify alcohol use, objective, specific and sensitive long-term alcohol markers are necessary. Ethyl glucuronide (EtG), a direct metabolite of alcohol, accumulates in keratinous matrices such as hair and nails, and is a specific and sensitive long-term biomarker for the detection of chronic alcohol consumption. So far, research has primarily focused on the detection of EtG in hair, and studies on its measurement in nails are scarce. In this article, we assessed EtG concentrations in hair, finger- and toenails from the same individuals in order to evaluate the direct correlation between the matrices. To this end, a total amount of 45 hair, 41 fingernail, and 13 toenail samples were collected from patients treated for alcohol use disorders at two psychiatric centers in Belgium. Samples were analyzed by gas chromatography-tandem mass spectrometry. Hair EtG concentrations ranged from <LLOQ to 1149pg/mg (median=164pg/mg, IQR [42; 283]). Fingernail EtG concentrations ranged from <LLOQ to 4090pg/mg (median=250pg/mg, IQR [74; 645]). Toenail EtG concentrations ranged from 127 to 3792pg/mg (median=687pg/mg, IQR [379; 1370]). EtG levels in hair and nails were significantly and positively correlated (p-values<0.001, r=0.70 and r=0.62, respectively). Higher concentrations were present in finger- and toenails compared to hair, which might be attributed to the slower growth rate of nails, resulting in increased accumulation of EtG. Hence, nail analysis may be interesting when low concentrations of EtG are expected, e.g. to discriminate between teetotalers and social drinkers. In addition, the current study proposes preliminary cut-off values for EtG concentrations in fingernails: >123pg/mg for chronic excessive alcohol consumption, 59-123pg/mg for moderate alcohol consumption, and <59pg/mg for alcohol abstinence. In light of these results, nails may be a useful alternative to hair samples for monitoring of long-term alcohol consumption, e.g., in cases where hair is not available. Further studies are needed to establish cut-off values for EtG levels in nails.

Systematic optimisation of ethyl glucuronide extraction conditions from scalp hair by design of experiments and its potential effect on cut‐off values appraisal

“…1 Moreover, EtG is nowadays extensively used as an effective biomarker to assess prolonged abstinence or chronic excessive alcohol consumption, provided that its determination is made on a keratin matrix, typically scalp hair. [7][8][9] In practice, the effectiveness of EtG determination in hair as a biomarker for chronic excessive alcohol consumption outperforms all the other alcohol biomarkers [10][11][12] to the extent that is frequently used as a unique laboratory testing. 6 Hair samples different from scalp hair can cautiously be analysed, in case scalp hair is not available or is degraded.…”

Bromazepam intoxication in an infant: Contribution of hair and nail analysis

“…Nail analysis is not routine practice, but may be useful when it is not possible to obtain head hair or body hair, in particular in the infant, or when external contamination of hair must be ruled out. A certain number of molecules and their metabolites have been identified and quantified in nails, in particular certain amphetamine, cannabinoid, opioid and cocaine derivatives, benzodiazepines, and ethylglucuronide . The impossibility of performing segmental analysis remains an important limitation.…”

Assessment of ethyl sulphate in hair as a marker for alcohol consumption using liquid chromatography–tandem mass spectrometry

“…Authentic hair samples ( n = 40) were analysed with the described, validated method to demonstrate its applicability for EtS measurements. Data on EtG concentrations in hair from the same patients were retrieved from our previous study . Analyses of both EtG and EtS in the hair samples allow assessing the relationship between these 2 markers in hair.…”

“…To evaluate the applicability of EtS as a biomarker of alcohol consumption, the method is applied to hair samples obtained from patients treated for alcohol use disorders. These results are compared to EtG concentrations in hair from the same patients …”