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🧪 Serum Osmolality (Calculated)

UseWork up hyponatraemia and suspected toxic alcohol ingestion.

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SourceStandard osmolal gap references

Runs locally in your browser (no PHI uploaded). For licensed clinicians — not a substitute for clinical judgement.
Stored on this device for revisit reminders

This-shift next steps

After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.

Scene next step
📋electrolyteOpen scene pack →
Related scores
Matching pathway
🧭hyperkOpen pathway →
Score + version; reference only — not a substitute for care · no HIS write

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Methodology · worked example, guidelines & full notes
Clinical takeaway

Osmolal gap = measured − calculated; > 10 suggests unmeasured osmoles.

When to use

Work up hyponatraemia and suspected toxic alcohol ingestion.

How it works

Calculated osmolality = 2·Na + glucose/18 + BUN/2.8 (+ ethanol/3.7), mg/dL units. Reference ~275–295 mOsm/kg.

Key points

  • Osmolal gap = measured − calculated; > 10 suggests unmeasured osmoles.
  • A raised gap may indicate methanol/ethylene glycol — urgent.
  • Add the ethanol term when measured.

References

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.

Sodium140 mmol/L
Glucose90 mg/dL
BUN14 mg/dL
Ethanol (optional)0 mg/dL

→Calculated osmolality290mOsm/kg

  • Formula：2·Na + glucose/18 + BUN/2.8
  • Reference：~275–295 mOsm/kg
Verification & sources · governance
FAQ

Frequently asked questions

What are the limits and cautions when using Serum Osmolality (Calculated)?
For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
Does Serum Osmolality (Calculated) 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 Serum Osmolality (Calculated) calculated in practice? Can you show a worked example?
Inputs: Sodium 140 mmol/L, Glucose 90 mg/dL, BUN 14 mg/dL, Ethanol (optional) 0 mg/dL → Result: Calculated osmolality 290 mOsm/kg（Formula: 2·Na + glucose/18 + BUN/2.8, Reference: ~275–295 mOsm/kg）
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