/Osmolar Gap

Osmolar Gap

Detects toxic alcohols in serum

Measured Osmolality
mOsm/kg
Sodium (Na)
mEq/L
Glucose
mg/dL
BUN
mg/dL

Total Score

0

Normal Osmolar Gap. Toxic alcohol ingestion unlikely.

-999+Low
10999+High

Disclaimer: The clinical scoring and algorithms on this platform are intended strictly for professional informational purposes. They do not constitute a definitive medical diagnosis, treatment, or clinical decision. The final judgment and responsibility lie with the treating physician.

Yasal Uyarı: Bu platformdaki klinik skorlamalar ve algoritmalar yalnızca sağlık profesyonellerini bilgilendirme amaçlıdır. Herhangi bir kesin tıbbi teşhis, tedavi veya klinik karar yerine geçemez. Nihai karar ve sorumluluk hastayı yatak başında değerlendiren hekime aittir.

Clinical Overview

The Osmolar Gap is the difference between the measured serum osmolality and the calculated osmolality. An elevated gap (>10 mOsm/kg) in the setting of unexplained metabolic acidosis strongly suggests the presence of unmeasured, osmotically active substances in the blood—most notably toxic alcohols like methanol or ethylene glycol.

Clinical Pearl

In late-presenting toxic alcohol ingestions, the parent alcohol may have already metabolized into toxic acids. At this stage, the Osmolar Gap may actually appear normal while the Anion Gap is severely elevated. Always evaluate both gaps together.

Pitfalls & Warnings

  • Serum osmolality must be measured using freezing point depression; vapor pressure methods will boil off volatile alcohols and falsely report a normal gap.
  • Severe lactic acidosis, DKA, or alcoholic ketoacidosis can also mildly elevate the gap.

Academic References

Kraut JA, Mullins ME. Toxic Alcohols. N Engl J Med. 2018;378(3):270-280.

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.

Disclaimer: The clinical scoring and algorithms on this platform are intended strictly for professional informational purposes. They do not constitute a definitive medical diagnosis, treatment, or clinical decision. The final judgment and responsibility lie with the treating physician.