Nine J S, Moraca M, Virji M A, Rao K N
Department of Pathology, University of Pittsburgh Medical Center, Pennsylvania, USA.
J Anal Toxicol. 1995 May-Jun;19(3):192-6. doi: 10.1093/jat/19.3.192.
Gas chromatography is considered to be the reference method for ethyl alcohol determination. However, enzymatic ethanol assays have been developed for use in the clinical laboratory by several commercial vendors. Essentially, these assays utilize the oxidation of ethyl alcohol to acetaldehyde with concurrent reduction of nicotinamide adenine dinucleotide (NAD) to NADH while monitoring the increase in absorbance at 340 nm. The increase in absorbance is theoretically proportional to the ethanol concentration in the sample. Previously, several authors reported that increased concentrations of lactate and lactate dehydrogenase (LDH) can cause false-positive results with certain enzymatic ethyl alcohol assays. In the present investigation, we further studied the interference of lactate and LDH in three enzymatic assays. Apparent ethyl alcohol concentrations in serum spiked with lactate and LDH, as well as patient and autopsy samples, were determined by the Syva, Abbott, and Roche enzymatic assays and by gas chromatography. The effect of coenzyme depletion on the rate of reaction and the interference of hemolysis were also investigated. Based on our results we suggest that coenzyme depletion plays a major role in the severity of the false-positive ethyl alcohol result, and the interference from hemolysis has a negligible effect on these results. We also confirm the previous studies in showing that elevated serum-lactate and LDH concentrations can result in varying degrees of false-positive ethyl alcohol concentrations in the three enzymatic assays. This should be taken into consideration in the management of patients in a tertiary care medical center.
气相色谱法被认为是测定乙醇的参考方法。然而，几家商业供应商已开发出酶法乙醇检测方法用于临床实验室。本质上，这些检测方法利用乙醇氧化为乙醛，同时烟酰胺腺嘌呤二核苷酸（NAD）还原为NADH，并监测340nm处吸光度的增加。吸光度的增加理论上与样品中的乙醇浓度成正比。此前，几位作者报道，乳酸和乳酸脱氢酶（LDH）浓度升高会导致某些酶法乙醇检测出现假阳性结果。在本研究中，我们进一步研究了乳酸和LDH在三种酶法检测中的干扰作用。通过Syva、雅培和罗氏酶法检测以及气相色谱法测定添加了乳酸和LDH的血清中表观乙醇浓度，以及患者和尸检样本中的乙醇浓度。还研究了辅酶耗竭对反应速率的影响以及溶血的干扰作用。基于我们的结果，我们认为辅酶耗竭在假阳性乙醇结果的严重程度中起主要作用，而溶血的干扰对这些结果的影响可忽略不计。我们还证实了先前的研究，即血清乳酸和LDH浓度升高会导致三种酶法检测中出现不同程度的假阳性乙醇浓度。在三级医疗中心对患者的管理中应考虑到这一点。
