Pitfalls of the alcohol dehydrogenase procedure for the emergency assay of alcohol: a case study of isopropanol overdose.

We describe a case of ethanol and isopropanol ingestion that resulted in coma. The concentration of ethanol and isopropanol was 0.90 and 1.65 g/liter in serum and 3.12 and 5.34 g/liter in gastric contents. With an enzymatic (alcohol dehydrogenase) method for ethanol determination we obtained erroneous analytical results. Because of partial cross reactivity with isopropanol, ethanol concentration was overestimated and total alcohol (i.e., the contribution of isopropanol) was underestimated. This was recognized by measuring serum osmolality. Differences between measured and calculated serum osmolality that are not accounted for by the serum ethanol concentration as determined by an enzymatic ethanol method must be further investigated by specific methods to see if other alcohols are present.