In a 55‑year‑old man with serum potassium 5.5 mmol/L and possible hyperkalaemia symptoms, should I repeat the potassium and obtain a 12‑lead ECG first or send him urgently to the emergency department?

Management of Potassium 5.5 mmol/L in an Asymptomatic 55-Year-Old Male

Repeat the potassium measurement immediately and obtain a 12-lead ECG before deciding on hospital transfer. A single elevated potassium reading at 5.5 mmol/L requires confirmation to rule out pseudohyperkalemia from hemolysis, and an ECG is essential to assess for cardiac conduction abnormalities that would mandate urgent intervention 1.

Immediate Assessment (Within Hours)

Verify the Result

• Repeat serum potassium immediately using a non-hemolyzed sample to exclude pseudohyperkalemia, which is the most common cause of falsely elevated readings 1, 2.
• Draw the sample carefully without prolonged tourniquet application or fist clenching to avoid spurious elevation 2.

Obtain 12-Lead ECG

• Perform ECG immediately to identify cardiac conduction disturbances, even in asymptomatic patients, as ECG changes may not correlate perfectly with serum potassium levels 2, 3.
• Look specifically for peaked T waves, prolonged PR interval, widened QRS complex, or loss of P waves—any of these findings mandate urgent hospital transfer regardless of symptoms 2, 4.

Decision Algorithm: Hospital vs. Outpatient Management

Send to Emergency Department if ANY of the following:

• ECG abnormalities present (peaked T waves, widened QRS, prolonged PR, absent P waves) 2, 4
• Confirmed potassium ≥6.0 mmol/L on repeat testing 1, 3
• Rapid rise in potassium (e.g., from normal to 5.5 mmol/L within hours to days), as this carries higher arrhythmia risk than chronic elevation 1
• High-risk comorbidities: chronic kidney disease (eGFR <60 mL/min), heart failure, diabetes mellitus, or structural heart disease 1, 5
• Concurrent use of multiple RAAS inhibitors (ACE inhibitor + ARB + aldosterone antagonist) 6, 3
• Symptomatic (muscle weakness, palpitations, paresthesias) despite your description of "asymptomatic" 2, 4

Outpatient Management Acceptable if ALL of the following:

• Confirmed potassium 5.5 mmol/L (not higher) on repeat non-hemolyzed sample 1
• Normal ECG with no conduction abnormalities 2, 3
• Truly asymptomatic with no muscle weakness, palpitations, or cardiac symptoms 2
• No high-risk comorbidities (normal renal function, no heart failure, no diabetes) 1, 5
• Reliable patient who can return for follow-up within 48-72 hours 1

Outpatient Management Protocol (If Criteria Met)

Medication Review (First Priority)

• Discontinue NSAIDs immediately if being used, as they impair renal potassium excretion and are a common culprit 6, 3.
• Stop potassium supplements and potassium-containing salt substitutes 2, 3.
• Review all medications for potassium-sparing diuretics (spironolactone, amiloride, triamterene), trimethoprim, or heparin 6, 2.
• If on ACE inhibitor or ARB: Do NOT discontinue at 5.5 mmol/L—current guidelines recommend dose adjustment only when potassium exceeds 5.5 mmol/L 1. However, if potassium remains 5.5 mmol/L on repeat, consider reducing dose by 50% 1.

Dietary Intervention

• Implement strict dietary potassium restriction to <3 g/day (77 mEq/day) by eliminating high-potassium foods: bananas, oranges, potatoes, tomatoes, processed foods, and salt substitutes 1, 2, 3.
• Provide written dietary counseling or refer to a renal dietitian 1.

Monitoring Schedule

• Recheck potassium and renal function within 48-72 hours (not the standard 4-month interval) 1, 3.
• If potassium normalizes to <5.0 mmol/L, continue weekly monitoring for 2-3 weeks, then monthly 1.
• If potassium remains >5.5 mmol/L despite interventions, escalate to hospital evaluation or consider potassium binders 1, 3.

Hospital Management (If Transfer Indicated)

Immediate Interventions (If ECG Changes Present)

• Calcium gluconate 10%: 1-2 grams (10-20 mL) IV over 2-5 minutes to stabilize cardiac membranes if ECG shows conduction abnormalities 2, 4.
• Insulin 10 units IV with 25 grams dextrose (D50W 50 mL) to shift potassium intracellularly, lowering serum potassium by 0.5-1.2 mEq/L within 30-60 minutes 1, 4.
• Albuterol 10-20 mg nebulized over 10 minutes to augment insulin effect 1, 4.

Subacute Hospital Management (If No ECG Changes)

• Initiate patiromer 8.4 g twice daily as the preferred potassium binder for moderate hyperkalemia (5.5-6.0 mmol/L), which reduces potassium by 0.87-0.97 mmol/L within 4 weeks 1.
• Avoid sodium polystyrene sulfonate (Kayexalate) for chronic management due to risk of intestinal ischemia and colonic necrosis 1, 3.
• Consider sodium zirconium cyclosilicate (SZC) 10 g three times daily for 48 hours as an alternative, then transition to 5-15 g daily for maintenance 1.

Critical Pitfalls to Avoid

• Do not ignore a single reading of 5.5 mmol/L without confirmation—but also do not overreact before verifying the result and obtaining an ECG 1, 2.
• Do not prematurely discontinue RAAS inhibitors (ACE inhibitors/ARBs) at 5.5 mmol/L, as current guidelines recommend dose reduction only above this threshold 1, 3.
• Do not assume asymptomatic means low-risk—ECG changes can occur without symptoms, and potassium 5.5 mmol/L is at the threshold where life-threatening arrhythmias become possible 1, 2, 4.
• Do not delay ECG while waiting for repeat potassium—cardiac conduction disturbances require immediate recognition 2, 4.
• Do not use chronic sodium polystyrene sulfonate if long-term management is needed—newer binders (patiromer, SZC) are safer and more effective 1, 3.

Target Potassium Range

• Aim for 4.0-5.0 mmol/L as the optimal range to minimize both cardiac arrhythmia risk and mortality 1, 3.
• Recent evidence suggests maintaining potassium ≤5.0 mmol/L is safer than previously believed, especially in patients with comorbidities 1.