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The following is a summary of “Ethanol and the Limitations of the Osmol Gap,” published in the January 2025 issue of Emergency Medicine by Marino et al.
The osmol gap aids in identifying toxic alcohol exposure, though the ideal ethanol correction for detecting other alcohols remains unclear.
Researchers conducted a retrospective study to examine the baseline osmol gap variations and validate 2 common ethanol correction factors.
They included 22 healthy individuals who received an oral ethanol dose based on body mass, targeting a peak blood ethanol concentration above 200 mg/dL. The laboratory values were measured before ethanol intake and at 2, 4, and 6 hours afterward. An osmol gap above 10 or below –10 was deemed abnormal, while a corrected osmol gap above 10 was classified as a false positive (after correction).
The results showed 4 out of 22 participants (18%) had an osmol gap above 10 at baseline. Across 66 time points (N=66) after ethanol ingestion, 14 abnormal osmol gap tests (21%) were identified using an ethanol correction factor of 4.6, while 31 abnormal tests (47%) were noted with the Purssell ethanol correction factor of 3.7. The mean difference between the baseline and post-ethanol corrected osmol gap was lower with the molecular weight correction factor of 4.6 compared to the Purssell factor of 3.7 (0.2 vs 11.0; P<.001).
Investigators concluded that an ethanol correction coefficient of 4.6 improved the clinical osmol gap input in cases of elevated osmol gap without alcohol ingestion, although with some remained variation.
Source: annemergmed.com/article/S0196-0644(24)01303-9/abstract
