[The osmotic gap in the diagnosis of alcoholic intoxication]

Sodium, urea, glucose and osmolality were determined in 50 hospitalized patients. Osmolality was calculated according to two different methods and compared with measured osmolality. Both methods showed equally close correlations (r = 0.87), and for clinical use we recommend the following simple formula: osmolality = 2 x sodium + glucose + urea. The two formulas studied were then used to calculate the osmolal gap (difference between measured and calculated osmolality) in 30 patients with ethanol intoxication, in order to estimate the blood alcohol concentration. For the equation: blood ethanol concentration (g/L) = osmolal gap/27 we found a very good correlation between calculated and measured ethanol levels (r = 0.95). Our data confirm previous reports that blood ethanol can be quickly and fairly exactly estimated by using the osmolal gap.