🚽 Stool Osmotic Gap
UseWhen to use: chronic watery diarrhea workup with stool electrolytes.
Strata>50 osmotic cue; <50 secretory cue (teaching cutoffs).
LimitsWhen not to use: old/unrefrigerated samples (osm drifts). · Pitfall: assuming 290 when measured osm available. · Integrate laxative and diet history.
SourceStandard stool osmotic-gap teaching
This-shift next steps
After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.
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Methodology · worked example, guidelines & full notes
2×(Na+K).
When to use
When to use: chronic watery diarrhea workup with stool electrolytes.
How it works
Gap = stool_osm − 2×(Na+K) (assume 290 if osm not measured).
Key points
- 2×(Na+K).
- >50 vs <50.
- Next: workup branch.
References
- Standard stool osmotic-gap teaching
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.
| Stool Na | 30 mEq/L |
|---|---|
| Stool K | 40 mEq/L |
| Measured stool osmolality (optional) | 290 mOsm/kg |
→Osmotic gap150mOsm/kg
- Osm used：290 (measured)
- 2×(Na+K)：140
- Cue：>50 — osmotic diarrhea cue (laxatives, malabsorption, Mg)
Verification & sources · governance
FAQ
Frequently asked questions
- Does Stool Osmotic 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 Stool Osmotic Gap calculated in practice? Can you show a worked example?
- Inputs: Stool Na 30 mEq/L, Stool K 40 mEq/L, Measured stool osmolality (optional) 290 mOsm/kg → Result: Osmotic gap 150 mOsm/kg（Osm used: 290 (measured), 2×(Na+K): 140, Cue: >50 — osmotic diarrhea cue (laxatives, malabsorption, Mg)）