In this hyperkalemia case study, I outline the importance of paying attention when medications are discontinued. EN is a 78-year-old female with chronic kidney disease stage 4, hypertension, heart failure with preserved ejection fraction, and type 2 diabetes. She had been on furosemide 40 mg twice daily for years to help with fluid management. Along with the furosemide, she was prescribed potassium chloride 20 mEq twice daily to prevent her potassium from dropping too low.
During a recent hospitalization, her renal function worsened. The medical team decided to stop her furosemide out of concern for further kidney injury. Unfortunately, her potassium supplement was continued without reassessing whether she still needed it.
Fast forward two weeks. EN ended up in the emergency department with weakness, muscle cramps, and a slow heart rate. Her potassium level was 6.8 mEq/L — severe hyperkalemia.
This type of situation happens more often than you might think. One medication gets discontinued, but the “paired” medication gets forgotten about. In this case, the furosemide (which wastes potassium) was stopped, but the potassium supplement kept going. Without the loop diuretic pulling potassium out, her supplement was now driving her potassium dangerously high. On top of that, our patient had multiple risk factors: advanced CKD, older age, and heart failure — all of which make it much harder for the body to clear potassium.
Pay Attention – Practice Pearls
- Anytime a diuretic is stopped, always ask yourself if the patient still needs potassium supplementation.
- Potassium supplements can be very appropriate, but they can also be very dangerous if the reason for using them is no longer there.
- CKD patients are at especially high risk of developing hyperkalemia (excellent board exam question) when supplements are continued unnecessarily.
- Pharmacists can play a huge role by catching these situations and suggesting deprescribing or closer monitoring.
This hyperkalemia case study is a classic example of how medications don’t exist in a vacuum. When one drug changes, it can ripple through the rest of the med list.
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