Hyperkalemia and AKI after a nephrotoxic drug combination
A 68-year-old Omani man with type 2 diabetes, hypertension and CKD stage 4 (baseline creatinine 180 µmol/L, eGFR 28 mL/min/1.73 m²) presents to primary care with 3 days of vomiting and poor oral intake. He has been taking ibuprofen 400 mg three times daily for knee pain, plus metformin 1 g twice daily, ramipril 10 mg daily, spironolactone 25 mg daily and furosemide 40 mg daily. BP 98/60 mmHg, pulse 104/min, temperature 36.8°C, dry mucous membranes, no pedal edema. ECG shows peaked T waves and QRS 108 ms. Labs: sodium 132 mmol/L, potassium 6.4 mmol/L, urea 28 mmol/L, creatinine 340 µmol/L, bicarbonate 16 mmol/L. He has passed no urine since yesterday. The clinic has ECG, point-of-care potassium and IV calcium, but no dialysis; the regional hospital is 45 minutes away by ambulance. He is alert and can give history.
1. Outline your first 30 minutes of management and list the medications that must be stopped immediately, with the reasoning for each action.
Read the worked answer
Priority: stabilize the myocardium, then lower potassium while arranging dialysis.
- Put on continuous cardiac monitor and obtain IV access; repeat ECG and point-of-care K after each intervention.
- Give IV calcium gluconate 10% 10–30 mL because peaked T waves and QRS 108 ms indicate membrane instability. Calcium does not lower K; it buys time.
- Give insulin 10 units IV with 25 g dextrose (50 mL of 50% dextrose), then check glucose hourly. This shifts K intracellularly. If glucose is already high, dextrose may be reduced but not omitted without monitoring.
- Add nebulized salbutamol 10–20 mg as an adjunct; it lowers K modestly while dialysis is arranged.
- Stop immediately: ibuprofen (NSAID-induced afferent vasoconstriction and hyperkalemia), metformin (contraindicated at eGFR <30 and with AKI; lactic acidosis risk), ramipril (ACE inhibitor worsens hyperkalemia and AKI), spironolactone (potassium-sparing diuretic), and furosemide (he is volume-depleted and oliguric; a diuretic will not help and may worsen prerenal injury).
- Give cautious isotonic saline only if he is clearly hypovolemic, in small boluses with reassessment; avoid large-volume resuscitation because he is oliguric.
- Do not give potassium-containing fluids. Treat acidosis only if severe or as a bridge; sodium bicarbonate is not a substitute for dialysis.
- Arrange urgent transfer to the regional hospital for dialysis; the clinic cannot definitively manage this.
Reasoning: The combination of AKI, oliguria, acidosis and ECG changes makes this a medical emergency even before K is repeated. Removing the offending drugs is as important as giving the temporizing treatments.
2. What criteria would make you activate urgent dialysis rather than continue medical management, and what would you monitor during the 45-minute transfer?
Read the worked answer
Activate urgent dialysis for refractory or dangerous hyperkalemia, not for a single number alone.
Indications in this man:
- K remains >6.0 mmol/L after calcium, insulin-dextrose and salbutamol, or ECG changes persist.
- Oliguria with creatinine 340 µmol/L, urea 28 mmol/L and bicarbonate 16 mmol/L - a mixed AKI/uremic picture that will not correct with drugs alone.
- Any complication of uremia (encephalopathy, pericarditis, bleeding) or volume overload that cannot be managed medically.
He does not need a tunneled line or formal nephrology consult before transfer; the receiving center can arrange urgent hemodialysis. If he were hemodynamically unstable, the transfer should be by ambulance with a clinician.
During transfer monitor: cardiac rhythm continuously, BP and pulse every 15 minutes, capillary glucose hourly for at least 4–6 hours after insulin, urine output, mental status, and repeat K on arrival. Have calcium gluconate available for recurrence. Avoid further NSAIDs, ACE inhibitors and potassium-sparing drugs. Document the time of insulin and glucose so the receiving team can anticipate rebound hypoglycemia.
Reasoning: Medical therapy shifts potassium but does not remove it. In oliguric AKI the total body potassium remains high, so dialysis is the definitive treatment; transfer should not be delayed while waiting for a normalized K.
3. At discharge after dialysis, how would you reconcile his medication list and set up follow-up to reduce the chance of another episode?
Read the worked answer
Medication reconciliation should be explicit and written, not verbal.
- Stop permanently: ibuprofen and all NSAIDs; metformin; spironolactone. Document the reasons on the discharge prescription.
- Hold now, reassess later: ramipril and furosemide. An ACE inhibitor may be restarted after recovery if he is stable, with potassium and creatinine checked 1–2 weeks later; it is not safe to restart blindly at discharge. Furosemide should be reviewed against his volume status.
- Pain: use paracetamol at a reduced maximum dose for CKD, topical NSAID or physiotherapy for knee pain, and avoid opioid accumulation. Do not substitute another NSAID.
- Diabetes: after metformin is stopped, he needs an alternative agent that is safe at eGFR 28; involve nephrology/diabetes team. Insulin may be needed if glucose is uncontrolled.
- Sick-day rules: stop ramipril and diuretics during vomiting or poor intake; seek review early. Give a written card.
- Monitoring: GP review in 48–72 hours with creatinine, potassium, bicarbonate and volume status; nephrology follow-up within 2 weeks; repeat ECG if K was abnormal.
- Prevention: avoid dehydration, review all new drugs for renal dosing, vaccinate, and educate the family. The discharge summary should flag the hyperkalemia and AKI as intolerances so future clinicians do not repeat the prescription.
Reasoning: The index event was largely drug-induced and preventable. Reconciliation must remove the nephrotoxic combination and create a monitoring plan, not simply list the old medications.