OSMOLAL AND ANION GAPS IN PATIENTS ADMITTED TO AN EMERGENCY MEDICAL DEPARTMENT

1 Osmolal and anion gaps are helpful in the diagnosis and evaluation o f intoxications with methanol and ethylene glycol, Reported reference values for osmolal gap and anion gap are -1 (+/- 6) mosm kg(-1) H2O an d 16 (+/- 2) mmol l(-1), respectively, However, we have repeatedly fou nd unexplained increased gaps in patients admitted to our department, and the relevance of the established reference values has been questio ned. 2 Osmolal and anion gaps were determined in an unselected populat ion of patients consecutively admitted to an emergency medical departm ent. In the case of unexplained gaps, the blood samples were analysed with respect to the presence of alcohols and organic acids. 3 We inclu ded all accessible patients admitted during 14 days. Appropriate blood samples were obtained in 177 patients (88 male, 89 female), with a me an age of 65 years (range 17-94). 4 The mean and (standard deviation) for osmolal and anion gaps in our material were 5.2 mosm kg(-1) H2O (7 .0) and 12.9 mmol/l (4.2). Neither methanol nor ethylene-glycol was de tected in serum from any patients, Small amounts of ethanol were found in 5 patients, and high lactate levels explained in part the most ext ensively increased anion gaps, However, the calculated analytical stan dard deviation accounted entirely for the variation in our material, a nd we suggest that the present reference values be adjusted.