Screening for alcohol intoxication by the osmolar gap.

Significant ethanol intoxication can be detected by measuring a large osmolar gap, i.e. a large difference between the measured and calculated plasma osmolality. In our laboratory, measurement of the osmolar gap with the application of a correction factor has been used as a screening test for alcohol intoxication and has been shown to be rapid and effective and to compare favourably with an accepted method for assaying ethanol (alcohol dehydrogenase). In only a few clinical situations is a more specific and accurate assay for ethanol required. In interpreting the result, it must be stressed that substances other than ethanol may occasionally cause a raised osmolar gap.