CKD G4 With Hyperkalemia and a Rising Creatinine: Which Kidney Medicines Continue?
Mr. R is a 63-year-old man with type 2 diabetes and CKD G4/A3 (baseline eGFR 24 mL/min/1.73 m², UACR 1,850 mg/g). His medications are lisinopril 20 mg daily, empagliflozin 10 mg daily, furosemide 40 mg daily, metformin 500 mg twice daily, and ibuprofen 400 mg as needed for knee pain. Today he reports two days of nausea and reduced oral intake. He has missed his furosemide for three days because of nausea and has been using ibuprofen more often. Vital signs: BP 148/86, HR 82, afebrile. Exam shows no orthostatic change, trace pedal edema, and normal lung sounds. Labs: potassium 6.1 mmol/L, bicarbonate 19 mmol/L, creatinine 3.1 mg/dL (baseline 2.7), glucose 168 mg/dL. ECG shows peaked T waves but no widened QRS. He asks whether he can keep taking his kidney medicines.
1. What is your immediate priority, and which clinical or ECG findings would make you treat this as an emergency rather than an outpatient problem?
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Immediate priority: this is hyperkalemia with ECG changes in a patient with advanced CKD and a new AKI. Peaked T waves are an early ECG sign; they warrant urgent treatment even without QRS widening, because progression to sine-wave morphology or ventricular arrhythmia is unpredictable. I would place him on continuous cardiac monitoring, repeat the ECG and stat potassium, and start three things: (1) IV calcium gluconate or calcium chloride if there are ECG changes or symptoms-peaked T waves with K 6.1 and AKI are enough to give calcium in most settings; (2) insulin plus glucose and nebulized albuterol to shift potassium intracellularly; (3) removal of potassium and treatment of the cause-stop ibuprofen, assess volume and resume diuretic if appropriate, correct acidosis, and consider a potassium binder.
Emergency findings: wide QRS, sine-wave pattern, bradycardia, hypotension, ventricular ectopy, or K ≥6.5 mmol/L with symptoms. He does not have those yet, but he should not be sent home without a repeat ECG and potassium after treatment.
2. Which medications should be stopped, continued, or adjusted today, and why? Address the NSAID, metformin, ACE inhibitor, SGLT2 inhibitor, and diuretic.
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Ibuprofen: stop. NSAIDs worsen AKI, blunt ACE inhibitor and diuretic effect, and raise potassium.
Metformin: hold/stop. eGFR is below 30 mL/min/1.73 m² and he now has AKI, increasing the risk of lactic acidosis.
Lisinopril: hold now, but do not permanently abandon it reflexively. With K 6.1 and AKI, the acute risk outweighs benefit. RAAS inhibitors still provide long-term kidney and cardiovascular protection, so once potassium is <5.0, creatinine is near baseline, and volume is stable, restart at a lower dose with close follow-up.
Empagliflozin: hold during acute illness, then reassess. SGLT2 inhibitors can cause volume depletion and euglycemic ketoacidosis during sickness. They are not the cause of hyperkalemia, and kidney benefit can persist at low eGFR, so this is usually a temporary hold rather than a permanent stop.
Furosemide: resume if he is volume-overloaded and making urine. He missed three days and has trace edema, but assess volume first because nausea and poor intake may mean he is dry.
Bicarbonate: with bicarbonate 19 mmol/L, consider oral bicarbonate replacement to correct metabolic acidosis, which also helps potassium control. Avoid potassium-containing salt substitutes.
3. One week later his potassium is 5.0 mmol/L and creatinine is 2.8 mg/dL. How would you safely reinitiate RAAS inhibitor therapy and monitor him?
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At K 5.0 and creatinine 2.8 mg/dL, he is near baseline but still at high risk. First confirm volume status and urine output, review for ongoing NSAID use, constipation, or high-potassium intake, and consider a potassium binder if needed to permit RAAS blockade. Restart lisinopril at a low dose-for example 5–10 mg daily-rather than immediately returning to 20 mg, then check potassium and creatinine in 1–2 weeks.
Reinforce sick-day rules: hold lisinopril, empagliflozin, metformin, and the diuretic during vomiting, diarrhea, or poor intake, and call the clinic. Continue the SGLT2 inhibitor when stable because it slows CKD progression, but monitor volume status. Arrange dietitian review and follow-up labs. If potassium rises again, use a potassium binder rather than abandoning RAAS blockade unless hyperkalemia is refractory.