🧪 Osmolal Gap
UseWhen to use: suspected toxic alcohol, unexplained AG acidosis, or osmolar mismatch.
Strata≤10 usual; >20 raises concern for toxic alcohols / other osmoles.
LimitsWhen not to use: after late presentation when parent alcohol cleared … · Pitfall: BUN vs urea unit mix-ups. · Send definitive toxicology early.
SourceStandard osmolal gap equation
This-shift next steps
After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.
Paste the link in Slack, Teams, X, or LinkedIn — the preview image comes from this page’s Open Graph card.
Methodology · worked example, guidelines & full notes
Measured − calculated.
When to use
When to use: suspected toxic alcohol, unexplained AG acidosis, or osmolar mismatch.
How it works
Gap = measured − (2·Na + glu/18 + BUN/2.8 [+ EtOH/4.6]).
Key points
- Measured − calculated.
- >20 high cue.
- Next: toxic alcohols panel.
References
- Standard osmolal gap equation
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Measured osmolality | 310 mOsm/kg |
|---|---|
| Sodium | 140 mmol/L |
| Glucose | 100 mg/dL |
| BUN | 14 mg/dL |
| Ethanol (optional) | 0 mg/dL |
→Osmolal gap19.4mOsm/kg
- Calculated osm：290.6 mOsm/kg
- Cue：Gap 10–20 — elevated; consider lab timing / mild unmeasured osmoles
Verification & sources · governance
FAQ
Frequently asked questions
- Does Osmolal Gap upload patient data? Where is it calculated?
- Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
- How is Osmolal Gap calculated in practice? Can you show a worked example?
- Inputs: Measured osmolality 310 mOsm/kg, Sodium 140 mmol/L, Glucose 100 mg/dL, BUN 14 mg/dL, Ethanol (optional) 0 mg/dL → Result: Osmolal gap 19.4 mOsm/kg（Calculated osm: 290.6 mOsm/kg, Cue: Gap 10–20 — elevated; consider lab timing / mild unmeasured osmoles）