MBBS OSCE · Nephrology / General Medicine
OSCE — assessment and emergency management of acute kidney injury with hyperkalaemia
An 8-minute OSCE station assessing the candidate's structured assessment of AKI — volume status, classification (pre-/intrinsic/post-renal), FENa interpretation, KDIGO staging, the hyperkalaemia emergency ladder, and the AEIOU dialysis indications.
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Brief (to candidate)
A 68-year-old diabetic woman is admitted with 3 days of diarrhoea and vomiting; she has been taking ibuprofen for back pain. She is drowsy,[1] pulse 110, BP 88/56, JVP low, with a dry mouth and reduced skin turgor. Bloods show creatinine 3.0 mg/dL (baseline 1.0), potassium 6.9 mmol/L, venous pH 7.18; the ECG shows wide peaked T waves. Urine output is 0.15 mL/kg/h. You have 8 minutes to assess her, classify and stage the AKI, and outline the immediate management.
Candidate instructions
- Take a focused history and examine using an ABCDE approach, paying attention to volume status and any obstructive signs.[1]
- Classify the AKI (pre-/intrinsic/post-renal) and state the KDIGO stage.
- Outline the immediate management, including the hyperkalaemia ladder with doses and the indications for renal replacement therapy.
- State your disposition (ward vs ICU) and the safety-net / follow-up advice.[3]
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| ABCDE / volume status[1] | Recognises hypovolaemia (tachycardia, hypotension, low JVP, dry mucosae); plans a fluid challenge 250-500 mL balanced crystalloid with reassessment |
| Hyperkalaemia emergency | Identifies K 6.9 with ECG changes as the immediate threat; gives calcium gluconate 10% 10 mL IV first; then insulin 10 units + 50% dextrose |
| Classification | Pre-renal (volume depletion + NSAID); excludes obstruction (history, examination, ultrasound) |
| KDIGO staging | Reproduces staging; creatinine 3.0x baseline = Stage 3 (worst criterion) |
| Stop nephrotoxins / drug review | Stops the NSAID; reviews all drugs for renal dosing |
| AEIOU | Reproduces the indications (acidosis, electrolytes, ingestion, overload, uraemia); states creatinine alone is NOT an indication |
| Communication & safety-net | Clear plan; ICU if shock/AEIOU; nephrology if intrinsic/rising; follow-up renal function (risk of future CKD) |
Model key actions
- Calcium gluconate 10% 10 mL IV for the hyperkalaemic ECG changes (stabilises the myocardium; does not lower potassium).[3]
- Fluid challenge (250-500 mL balanced crystalloid) to restore perfusion; stop the NSAID; treat the GI losses.[1]
- Classify pre-renal (FENa under 1% expected); KDIGO Stage 3 (creatinine 3.0x baseline).[1]
- AEIOU drives dialysis — this patient's hyperkalaemia should resolve medically; dialyse only if refractory.[2]
- Refer to nephrology/ICU for shock or an AEIOU indication; follow up renal function — AKI survivors risk future CKD.[3]
Common errors
- Treating the creatinine before the potassium — the ECG changes make hyperkalaemia the lethal, immediate problem.
- Not recognising volume depletion — failing to give a fluid challenge in a clearly pre-renal AKI.
- Continuing the NSAID or other nephrotoxins.
- Dialysing for a creatinine number rather than an AEIOU indication.
- Missing obstruction — not requesting an ultrasound or checking bladder/urinary symptoms.[3]
References3ShowHide
- [1]Kellum JA, Lameire N Diagnosis, evaluation, and management of acute kidney injury: a KDIGO summary (Part 1). Critical Care, 2013.PMID 23394211
- [2]Lameire N, Kellum JA Contrast-induced acute kidney injury and renal support for acute kidney injury: a KDIGO summary (Part 2). Critical Care, 2013.PMID 23394215
- [3]Ronco C, Bellomo R, Kellum JA. Acute kidney injury. Lancet, 2019.PMID 31777389