By how much do ACE inhibitors (angiotensin‑converting enzyme inhibitors) or angiotensin‑II receptor blockers (ARBs) raise serum potassium?

Potassium Increase with ACE Inhibitors and ARBs

ACE inhibitors and ARBs typically increase serum potassium by approximately 0.1 to 0.3 mEq/L (mmol/L) in most patients, with the rise being modest and generally clinically insignificant in those without risk factors. 1

Expected Potassium Changes in Different Populations

Low-Risk Patients (Hypertension Without Comorbidities)

• In patients with hypertension and no risk factors for hyperkalemia, ACE inhibitor or ARB monotherapy causes small increases in serum potassium of approximately 0.1 to 0.3 mmol/L. 1
• The incidence of hyperkalemia (potassium >5.5 mEq/L) is low at ≤2% with monotherapy in this population. 1
• Only 6.4% of patients treated with enalapril in the SOLVD trials developed serum potassium ≥5.5 mEq/L. 2

High-Risk Patients (Heart Failure or CKD)

• Patients with heart failure or chronic kidney disease experience higher rates of hyperkalemia at 5% to 10%, but the absolute increase in serum potassium remains small at approximately 0.1 to 0.3 mmol/L. 1
• In ambulatory patients with CKD stage 3, the incidence of hyperkalemia (potassium ≥5.5 mEq/L) was 3.1%, rising to 13.7% in CKD stage 4. 3
• Despite higher rates in advanced CKD, study discontinuation due to hyperkalemia remains low at 1% to 5% even in high-risk groups. 1

Dual RAAS Blockade

• Combining ACE inhibitors or ARBs with other RAAS inhibitors increases hyperkalemia incidence to approximately 5%. 1
• Adding spironolactone to ACE inhibitor or ARB therapy increases mean serum potassium by only 0.19 mEq/L (95% CI, 0.12-0.26 mEq/L) compared to ACE inhibitor/ARB alone. 4

Clinical Context and Risk Factors

The magnitude of potassium increase depends heavily on baseline renal function and concurrent medications rather than the ACE inhibitor or ARB itself. 3

Key Risk Factors for Greater Potassium Elevation

• Reduced GFR: The propensity for hyperkalemia is incremental with declining GFR, requiring caution in advancing stages of CKD. 3
• Low body mass index: BMI is an independent risk factor for hyperkalemia with ACE inhibitor/ARB treatment. 5
• Age >65 years: Elderly patients have increased risk independent of other factors. 5
• Baseline hyponatremia: Serum sodium <135 mEq/L predicts higher hyperkalemia risk. 5
• Concurrent medications: Concomitant use of aldosterone antagonists, potassium-sparing diuretics, NSAIDs, or potassium supplements significantly increases risk. 5, 3
• History of prior hyperkalemia treatment: Previous episodes predict recurrence. 5

Monitoring Recommendations

Serum potassium and creatinine should be checked 2-4 weeks after initiating or increasing ACE inhibitor/ARB dose, with earlier monitoring (1-2 weeks) if baseline eGFR <30 mL/min/1.73 m² or baseline potassium >4.5 mEq/L. 6

• For patients treated with ACE inhibitors, ARBs, or diuretics, monitor serum creatinine/eGFR and potassium at least annually. 2
• In patients with eGFR <60 mL/min/1.73 m², check serum potassium periodically with more frequent monitoring every 3-6 months. 7, 8
• After any dose increase, restart the monitoring cycle with labs at 2-4 weeks. 6

Important Clinical Caveats

Diabetes mellitus does not independently affect the incidence of hyperkalemia beyond its effect on GFR. 3 This is a common misconception—diabetic patients are not at higher risk when GFR is accounted for.

Adequate dietary potassium intake does not cause hyperkalemia in hypertensive individuals with normal renal function taking ACE inhibitors or ARBs. 9 A study increasing dietary potassium from 3775 mg/d to 5212 mg/d over 4 weeks showed no significant increase in serum potassium despite ACE inhibitor/ARB therapy. 9

The small potassium increases are generally not clinically significant and should not prevent use of these medications in patients who would benefit from RAAS inhibition. 1 Rather than denying effective treatment, electrolyte levels should be closely monitored. 1

Management Algorithm for Elevated Potassium

Serum K⁺ (mEq/L)	Action
5.0-5.5	Dietary potassium restriction; stop potassium supplements and potassium-sparing diuretics; add or increase loop/thiazide diuretics; continue ACE inhibitor/ARB at current dose. [6]
>5.5-6.0	Reduce ACE inhibitor/ARB dose by 50% and recheck potassium in 1-2 weeks. If potassium remains >5.5 mEq/L, discontinue. [6]
≥6.0	Discontinue ACE inhibitor/ARB immediately and initiate acute hyperkalemia treatment. [6]

ACE inhibitors and ARBs should be given with caution to patients with elevated serum potassium (>5.0 mEq/L) at baseline. 2 However, hyperkalemia should be managed with dietary restriction, diuretics, or cation exchangers rather than routine ACE inhibitor cessation. 6