🧪 Urine Osmolal Gap
UseWhen to use: hyperchloremic metabolic acidosis / RTA workup.
StrataLow UOG suggests low NH₄⁺ response; high UOG suggests ammonium/unmeasured osmoles.
LimitsWhen not to use: unknown urea units. · Pitfall: UN mg/dL without /2.8. · Cut-points vary by lab.
SourceStandard urine osmolal gap teaching formula
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
Unit-aware UOG.
When to use
When to use: hyperchloremic metabolic acidosis / RTA workup.
How it works
UOG = Uosm − [2(UNa+UK) + urea + glucose].
Key points
- Unit-aware UOG.
- RTA adjunct.
- Next: urine pH / AG.
References
- Standard urine osmolal gap teaching formula
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 urine osmolality | 500 mOsm/kg |
|---|---|
| Urine Na | 40 mmol/L |
| Urine K | 30 mmol/L |
| Urea / UN input | Urea mmol/L |
| Urea or UN value | 200 mmol/L or mg/dL |
| Glucose input | Glucose mg/dL → /18 |
| Urine glucose (if used) | 0 mmol/L or mg/dL |
→Urine osmolal gap160mOsm/kg
- Calculated Uosm：340 mOsm/kg
- Cue：Intermediate UOG — interpret with pH, AG, clinical acid–base
| Measured urine osmolality | 500 mOsm/kg |
|---|---|
| Urine Na | 40 mmol/L |
| Urine K | 30 mmol/L |
| Urea / UN input | Urine urea nitrogen (UN) mg/dL → /2.8 |
| Urea or UN value | 200 mmol/L or mg/dL |
| Glucose input | Ignore glucose (≈0) |
| Urine glucose (if used) | 0 mmol/L or mg/dL |
→Urine osmolal gap289mOsm/kg
- Calculated Uosm：211 mOsm/kg
- Cue：Intermediate UOG — interpret with pH, AG, clinical acid–base
Verification & sources · governance
FAQ
Frequently asked questions
- Does Urine 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 Urine Osmolal Gap calculated in practice? Can you show a worked example?
- Inputs: Measured urine osmolality 500 mOsm/kg, Urine Na 40 mmol/L, Urine K 30 mmol/L, Urea / UN input Urea mmol/L, Urea or UN value 200 mmol/L or mg/dL, Glucose input Glucose mg/dL → /18, Urine glucose (if used) 0 mmol/L or mg/dL → Result: Urine osmolal gap 160 mOsm/kg（Calculated Uosm: 340 mOsm/kg, Cue: Intermediate UOG — interpret with pH, AG, clinical acid–base） Inputs: Measured urine osmolality 500 mOsm/kg, Urine Na 40 mmol/L, Urine K 30 mmol/L, Urea / UN input Urine urea nitrogen (UN) mg/dL → /2.8, Urea or UN value 200 mmol/L or mg/dL, Glucose input Ignore glucose (≈0), Urine glucose (if used) 0 mmol/L or mg/dL → Result: Urine osmolal gap 289 mOsm/kg（Calculated Uosm: 211 mOsm/kg, Cue: Intermediate UOG — interpret with pH, AG, clinical acid–base）