Which medication should be discontinued in a patient with diabetes, hypertension, and chronic heart failure, presenting with DVT, hyperkalemia, and taking insulin, furosemide, enalapril, and heparin?

Discontinue Enalapril Immediately

Enalapril (Option B) should be discontinued immediately in this patient with severe hyperkalemia (K+ 6.0 mmol/L), elevated creatinine (120 μmol/L), and diabetes mellitus with chronic heart failure. This represents a life-threatening electrolyte emergency directly caused by ACE inhibitor therapy in a high-risk patient.

Why Enalapril Must Be Stopped

The combination of diabetes, chronic heart failure, and renal impairment creates the perfect storm for ACE inhibitor-induced hyperkalemia. 1 The European Society of Cardiology explicitly recommends discontinuing or reducing RAAS inhibitors immediately when K+ >6.5 mEq/L, and this patient at 6.0 mEq/L with multiple risk factors warrants immediate action 1, 2, 3.

Critical Risk Factors Present:

• Severe hyperkalemia (6.0 mmol/L) - classified as moderate-to-severe requiring immediate intervention 1, 3
• Diabetes mellitus - amplifies hyperkalemia risk with ACE inhibitors 1, 4
• Elevated creatinine (120 μmol/L) - indicates renal impairment, dramatically increasing hyperkalemia risk 1, 5
• Chronic heart failure - further increases risk when combined with ACE inhibitors 1, 4

The FDA label for enalapril specifically warns that hyperkalemia >5.7 mEq/L occurs in approximately 1% of hypertensive patients, with risk factors including renal insufficiency, diabetes mellitus, and concomitant use of potassium-affecting medications 5. This patient has ALL these risk factors simultaneously.

Why Other Medications Should Continue

Insulin (Option A) - Continue

Insulin is safe and essential in this clinical context. The American Heart Association confirms insulin is safe to use in patients with renal impairment, though lower doses may be needed 1. Insulin actually helps treat hyperkalemia by driving potassium intracellularly 3. Stopping insulin would worsen glycemic control and provide no benefit for the hyperkalemia.

Heparin (Option C) - Continue

While heparin can theoretically cause hyperkalemia through aldosterone suppression, this effect typically requires prolonged use (>7 days) and is far less pronounced than ACE inhibitor-induced hyperkalemia 2. The patient's DVT requires continued anticoagulation - the acute thrombotic risk outweighs the minimal contribution of heparin to hyperkalemia in this acute setting. The hyperkalemia is clearly attributable to enalapril given the patient's risk profile.

Furosemide (Option D) - Continue and Potentially Increase

Loop diuretics like furosemide actually REDUCE hyperkalemia risk by promoting urinary potassium excretion 2, 6. The European Society of Cardiology explicitly recommends continuing thiazide/loop diuretics to promote potassium excretion and help lower serum potassium 1, 2. In fact, furosemide should likely be continued or even increased to enhance renal potassium elimination 3.

Immediate Management Algorithm

1. Discontinue enalapril immediately 1, 2, 3
2. Obtain ECG urgently to assess for hyperkalemia-related changes (peaked T waves, widened QRS) 3
3. If ECG changes present: Administer IV calcium gluconate for cardiac membrane stabilization 3
4. Continue furosemide (or increase dose) to enhance urinary potassium excretion 1, 2, 3
5. Recheck potassium and creatinine within 24-48 hours after stopping enalapril 2, 3
6. Initiate dietary potassium restriction (<3g/day) 3
7. Consider potassium binders (patiromer or sodium zirconium cyclosilicate) if K+ remains >5.5 mEq/L after stopping enalapril 2, 7

Critical Evidence Supporting This Decision

Multiple studies demonstrate the severe risk of ACE inhibitors in this exact clinical scenario:

• ATMOSPHERE trial: Hyperkalemia >6.0 mEq/L occurred in nearly 4% of diabetic heart failure patients on enalapril 1
• SOLVD trials: Independent predictors of hyperkalemia included enalapril use, baseline creatinine elevation, diabetes, and heart failure - this patient has ALL four 4
• Case reports: Reversible hyperkalemia and acute renal failure have been documented in diabetic patients with mild renal failure treated with enalapril, even after years of stable therapy 8, 9

Common Pitfalls to Avoid

Do not permanently abandon RAAS inhibition. Once potassium normalizes to 4.0-5.0 mEq/L, consider reintroducing enalapril at a lower dose (5 mg daily) with close monitoring, or switch to alternative antihypertensive agents (calcium channel blockers like amlodipine) 2. Newer potassium binders can enable continuation of RAAS inhibitors in patients requiring them for cardio-renal protection 2, 7.

Do not stop furosemide - this would worsen both the heart failure and the hyperkalemia 1, 2, 6.

Do not delay treatment waiting for repeat labs if ECG changes are present - severe hyperkalemia is a medical emergency 3.