What is the workup for hyperkalemia (elevated potassium level)?

Hyperkalemia Workup for Potassium 6.3 mEq/L

A potassium level of 6.3 mEq/L requires immediate evaluation and management, with discontinuation of any RAAS inhibitors and implementation of urgent potassium-lowering strategies. 1, 2

Initial Assessment

• ECG evaluation: Immediately check for cardiac manifestations of hyperkalemia:

  • Peaked T waves
  • PR interval prolongation
  • QRS widening
  • Sine wave pattern (in severe cases)

• Clinical evaluation: Assess for:

  • Muscle weakness
  • Paresthesias
  • Cardiac symptoms (palpitations, chest pain)
  • Signs of underlying conditions (heart failure, renal disease)

Immediate Management for K+ 6.3 mEq/L

1. Cardiac membrane stabilization (if ECG changes present):

   • Calcium chloride 10% 5-10 mL IV over 2-5 minutes OR
   • Calcium gluconate 10% 15-30 mL IV over 2-5 minutes 2

2. Intracellular shift of potassium:

   • Insulin 10 units IV with glucose 25g (if not hyperglycemic) 2, 3
   • Albuterol 10-20 mg nebulized 2, 4
   • Sodium bicarbonate 50 mEq IV (if metabolic acidosis present) 4

3. Potassium elimination:

   • Initiate potassium binder therapy:
     • Patiromer 8.4g once daily OR
     • Sodium zirconium cyclosilicate (SZC) 10g three times daily for 48 hours, then 5-10g daily 2
   • Loop diuretics (if renal function permits)
   • Consider hemodialysis if severe, refractory, or patient has renal failure 4

Medication Review and Adjustment

• Discontinue medications that increase potassium:

  • RAAS inhibitors (ACEIs, ARBs, MRAs) should be stopped when K+ >6.0 mEq/L 1
  • Potassium-sparing diuretics
  • NSAIDs
  • Trimethoprim
  • Beta-blockers
  • Heparin 5, 6

• Eliminate potassium supplements and advise low-potassium diet 1

Diagnostic Workup for Underlying Causes

1. Laboratory assessment:

   • Repeat serum potassium (rule out pseudo-hyperkalemia)
   • Renal function tests (BUN, creatinine, eGFR)
   • Urinalysis
   • Serum glucose
   • Acid-base status (venous or arterial blood gas)
   • Serum magnesium and calcium levels

2. Identify risk factors:

   • Decreased renal function (eGFR <50 ml/min increases risk 5-fold) 5
   • Diabetes mellitus
   • Heart failure
   • Medication use (especially combinations of potassium-influencing drugs)
   • Advanced age 2, 5

Follow-up Monitoring

• Recheck serum potassium within 24-48 hours after initiating treatment 2
• Monitor potassium levels weekly initially, then monthly once stabilized
• Monitor renal function, magnesium, calcium, and sodium levels in patients on potassium binders 2

Common Pitfalls to Avoid

• Failing to recognize pseudo-hyperkalemia (hemolysis during blood draw)
• Discontinuing beneficial medications rather than adjusting doses
• Inadequate monitoring after initiating treatment
• Not considering the U-shaped mortality risk curve (both hypo- and hyperkalemia increase mortality) 1, 2
• Using sodium polystyrene sulfonate (SPS) for prolonged periods (risk of bowel necrosis, especially in elderly) 1, 2

Special Considerations

• Patients with heart failure, chronic kidney disease, or diabetes have significantly higher mortality risk with elevated potassium levels 1, 2
• Persistently elevated potassium levels are associated with higher mortality; normalization improves outcomes 2
• Consider reintroducing RAAS inhibitors at lower doses after potassium normalizes, especially in heart failure patients where these medications provide mortality benefit 1