Preliminary immunochemical test for the determination of ethyl glucuronide in serum and urine: comparison of screening method results with gas chromatography-mass spectrometry.

Ethyl glucuronide is a highly specific metabolite of ethanol that is formed by enzymatic conjugation of ethanol with glucuronic acid. Because of its suitability as a marker of excessive alcohol consumption in serum with low blood-alcohol concentration and as a consumption marker in serum and urine, especially after the breakdown of ethanol, demand exists for a simple and fast analytical procedure, which is rarely possible using mass spectrometric determination methods. For this reason, we developed an immunochemical screening procedure (ELISA) in which polyclonal antibodies are bound to the walls of microtiter plates. To test suitability, 335 authentic serum and 186 urine samples were examined using immunochemistry and gas chromatography-mass spectrometry (GC-MS). The serum (urine) samples with cutoff values of 0.31 mg/L (1.33 mg/L) yielded false-negative results in 9.5% (24.3%) and false positives in 8.4% (23.2%) of cases. Specificity was calculated at 91.6% (76.8%) and sensitivity at 90.5% (75.7%). Test efficiency was 90.8% (76.3%). The study shows that ethyl glucuronide and therefore alcohol consumption can be detected in immunochemical screening of serum in a similar manner as current drugs, but the method is of limited value for urine. A GC-MS confirmation continues to remain a necessity.