Toxic Alcohol: Osmolar Gap + Fomepizole Indication
Toxic-alcohol osmolar gap (Smithline 1976) with the AACT fomepizole indication: calculated osmolality, signed osmolar gap, and which indication limb is met.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Measured serum osmolality
- 305 mOsm/kg
- Serum sodium
- 140 mEq/L
- Glucose
- 90 mg/dL
- BUN
- 14 mg/dL
- Recent-ingestion history
- Yes
Result: Calculated osmolality 290 mOsm/kg, osmolar gap 15; fomepizole indicated (recent ingestion + gap over 10).
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Documented level over 20 mg/dL
- Fomepizole indicated (known plasma methanol or ethylene glycol).
- Recent ingestion + gap over 10
- Fomepizole indicated on history plus an elevated osmolar gap.
- Strong suspicion + 2 of 3
- pH under 7.3, bicarbonate under 20, osmolar gap over 10.
- Normal gap
- Does NOT exclude toxic alcohol once metabolized to acids; the anion gap rises instead.
What you enter
- Measured serum osmolality
- Serum sodium
- Glucose
- BUN
- Serum ethanol (optional)
- Arterial pH (optional)
- Serum bicarbonate (optional)
- Documented methanol / ethylene-glycol level (optional)
The other 2 fields
- Recent-ingestion history
- Strong clinical suspicion
How this is calculated
Smithline N, Gardner KD. Gaps - anionic and osmolal. JAMA. 1976;236(14):1594-1597. Treatment indication: Barceloux DG, et al (AACT) methanol (2002) and ethylene glycol (1999) practice guidelines. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.