False-positive ethanol blood concentrations leading to clinical confusion on Christmas Day

A case of altered consciousness in which ethanol ingestion was one of the differential diagnoses is described. Three separate blood samples were conveyed to the hospital biochemistry laboratory and each returned a positive value when assayed via an indirect, enzymatic method. The family strongly denied alcohol ingestion and hence, a few days later, the samples were conveyed to an external laboratory using a ‘specific’, chromatographic method. These samples were all reported as negative for ethanol. Alternative causes of altered consciousness were restricted by the false-positive ethanol laboratory results.