Clinical Insight: The Silent ECG Trap
A short high-stakes case built to test whether you recognize a dangerous electrolyte pattern before deterioration occurs.
A 67-year-old man with chronic kidney disease presents to the emergency department for generalized weakness and lightheadedness. He recently started trimethoprim-sulfamethoxazole for a skin infection. Physical examination shows mild bradycardia. Laboratory studies show potassium 7.9 mEq/L. ECG is shown below. Click or tap the plus sign to zoom.
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Treatment: IV calcium gluconate
The clinical presentation is most consistent with severe hyperkalemia with ECG changes. The most urgent initial treatment is IV calcium gluconate to stabilize the cardiac membrane. This does not lower serum potassium, but it reduces the risk of malignant arrhythmia while potassium-shifting and potassium-removing therapies are initiated.
- Key clue: hyperkalemia with peaked T waves is a cardiac emergency.
- First move: IV calcium gluconate stabilizes the myocardium when ECG changes are present.
- Next therapies: insulin with glucose and albuterol shift potassium intracellularly.
- Definitive removal: diuretics, potassium binders, or dialysis may be needed depending on severity and renal function.
References
- 1. Mount DB. Treatment and prevention of hyperkalemia in adults. In: Sterns RH, ed. UpToDate. Forman JP, ed. Waltham, MA: UpToDate Inc. https://www.uptodate.com. Accessed June 13, 2025.
- 2. Evans M, Lewis RD, Morgan AR, et al. A Narrative Review of Chronic Kidney Disease in Clinical Practice: Current Challenges and Future Perspectives. Adv Ther. 2022;39(1):33-43. doi:10.1007/s12325-021-01927-z. Accessed June 13, 2025.
- 3. Nauck MA, Quast DR, Wefers J, Meier JJ. GLP-1 receptor agonists in the treatment of type 2 diabetes - state-of-the-art. Mol Metab. 2021;46:101102. doi:10.1016/j.molmet.2020.101102. Accessed November 24, 2024.
- 4. Chapter 176: Diabetes Mellitus. In: Kasper DLD, Fauci ASA, Hauser SLS, et al, eds. Harrison's Manual of Medicine. McGraw Hill Inc.; 2020. https://harrisons.unboundmedicine.com/harrisons/view/Harrisons-Manual-of-Medicine/623095/all/type 2. Accessed November 24, 2024.
- 5. 12-lead ECG from a man presenting with chronic kidney disease, generalized weakness, and severe electrolyte abnormality. Courtesy of Dr. Michael-Joseph F. Agbayani and Dr. Eddieson Gonzales (Manila, Philippines). Creative Commons Attribution 4.0 via Wikimedia Commons. https://commons.wikimedia.org/wiki/File:HyperkalemiaECG.jpg. Accessed May 13, 2026.
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