Impaired diagnostic accuracy of hair ethyl glucuronide testing in patients with renal dysfunction

The impact of renal impairment and hemodialysis on ethyl glucuronide concentrations in hair (hEtG) is not well known. Here, hEtG levels were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in patients presenting to the transplant outpatient clinic and compared with the self-reported alcohol consumption in an anonymous validated questionnaire. Estimated daily alcohol intake (EDI) was calculated. A total of 94 patients with varying renal function (Glomerular filtration rate (GFR) > 60 mL/min: group 1 (n = 47); GFR 30-60 ml/min: group 2 (n = 29); GFR < 30 mL/min: group 3 (n = 18)) were included in the study. Fifteen of 18 (83.3%) patients in group 3 were on dialysis. Altogether, hEtG tested positive (> 5 pg/mg) in 25.5% (n = 24) of patients, while 36.2% (n = 34) and 14.9% (n = 14) of patients reported any or regular (> 10 g/d) alcohol consumption, respectively. The median hEtG concentration of positive samples was much higher in patients in group 3 with advanced renal dysfunction or on dialysis than in patients in group 1 or 2 (group 1, 2, 3 dialysis patients: 74, 52, 145 and 155 pg/mg, respectively), although they consumed on average much less alcohol per day (median EDI group 1, 2, 3, dialysis patients: 16, 17, 3 and 3 g/d, respectively). Also, there was a significant correlation between the hEtG concentration and EDI for patients in group 1 (ρ = 0.84; p = 0.01), but not for patients in group 2 (ρ = -0.35, p = 0.39) or 3 (ρ = 0.02, p = 0.96). Furthermore, the ability of hEtG to correctly identify abstainers as such was lower for patients with advanced renal dysfunction than for the remaining patients (specificity for group 1, 2, 3: 92%, 87%, 82%, respectively). So, monitoring hEtG concentration was less reliable in patients with advanced renal dysfunction or on hemodialysis and by far overestimated the amount of alcohol consumed.