Osmolar Gap

Name: Osmolar Gap
Creator: Daniel Diaz-Gil, MD
Keywords: osmolar gap, osmolal gap, osmolarity, osmolality, toxic alcohol, methanol, ethylene glycol, isopropanol, poisoning, toxicology

Calculates serum osmolar gap to screen for toxic alcohol ingestion (methanol, ethylene glycol)

Clinically Verified· 5 tests

For educational and informational purposes only. Verify all results before clinical application.

Measured Serum Osmolality *

mOsm/kg

Sodium (Na) *

mEq/L

Glucose *

mg/dL

BUN *

mg/dL

Ethanol Level

mg/dL

Optional: enter 0 if not available or no ethanol exposure

References

Purssell RA, Pudek M, Brubacher J, Abu-Laban RB. Derivation and validation of a formula to calculate the contribution of ethanol to the osmolal gap. Ann Emerg Med. 2001;38(6):653-659.[DOI]
Kraut JA, Xing SX. Approach to the evaluation of a patient with an increased serum osmolal gap and high-anion-gap metabolic acidosis. Am J Kidney Dis. 2011;58(3):480-484.[DOI]

Reviewed by Daniel Diaz-Gil, MD · Last updated March 2026

Medical disclaimer

This tool is for educational and informational purposes only. It is not a substitute for professional clinical judgment. Always independently verify results before making clinical decisions.

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