What is the management for a 28-day-old infant with hyperkalemia (elevated potassium level) possibly due to hemolysis?

Management of Hyperkalemia in a 28-Day-Old Infant with Possible Hemolysis

For a 28-day-old infant with a potassium level of 7.1 mmol/L that is possibly hemolyzed, the first step should be to repeat the test to confirm true hyperkalemia before initiating treatment, as pseudohyperkalemia is common in hemolyzed samples.

Initial Assessment

Confirm True Hyperkalemia

1. Repeat potassium measurement using proper collection technique

   • Collect blood without excessive muscle contraction or venous stasis 1
   • Use appropriate-sized needle (≥20-gauge if possible) 2
   • Consider venous blood gas analysis for rapid assessment 1
   • Check ECG for signs of hyperkalemia (peaked T waves, widened QRS) 1

2. Evaluate for pseudohyperkalemia

   • Hemolysis is the most common cause of falsely elevated potassium 3
   • In pediatric patients with hemolyzed samples showing hyperkalemia, 97.9% have normal potassium on repeat testing 4
   • Check for other causes: excessive muscle movement during collection, thrombocytosis, leukocytosis 3

Management Algorithm for Confirmed Hyperkalemia (K+ > 7 mmol/L)

Step 1: Assess for Cardiac Toxicity

• If ECG changes or cardiac symptoms present, proceed immediately to stabilization

Step 2: Cardiac Stabilization (if needed)

• Calcium chloride: 20 mg/kg (0.2 mL/kg of 10% solution) IV/IO 5
  • Give by slow push for cardiac protection
  • Calcium gluconate (60 mg/kg) may be substituted if calcium chloride unavailable
  • Protects cardiac membrane but does not lower potassium

Step 3: Shift Potassium into Cells

• Sodium bicarbonate: 1-2 mEq/kg IV/IO given slowly 5

  • Especially useful if metabolic acidosis present
  • Do not mix with calcium

• Insulin with glucose: Consider in consultation with pediatric specialist

  • Promotes potassium entry into cells

Step 4: Remove Excess Potassium

• Loop diuretics if renal function adequate
• Consider consultation for dialysis in severe cases with renal dysfunction

Risk Factors to Evaluate

1. Non-oliguric hyperkalemia risk factors 5, 6

   • Extreme prematurity (not applicable to this 28-day-old)
   • Systemic acidosis
   • Birth asphyxia
   • Massive hematomas
   • Hemolysis
   • Catabolic state

2. Other causes to consider 5

   • Renal dysfunction (check BUN/creatinine)
   • Medications (potassium-sparing diuretics, ACE inhibitors)
   • Adrenal insufficiency
   • Transfusion-related (if recent)

Prevention and Monitoring

• Monitor potassium levels closely after treatment
• If true hyperkalemia confirmed, limit potassium intake to 40-120 mg/kg/day (1-3 mmol/kg/day) 5
• For infants, consider formula type and volume (breast milk has lower potassium than formula) 5
• Monitor for fluid and electrolyte balance

Key Considerations for Neonates

• Neonates are particularly susceptible to both true hyperkalemia and pseudohyperkalemia
• Proper blood collection technique is crucial to avoid false elevations
• Rapid treatment is essential for true hyperkalemia due to risk of cardiac arrhythmias
• Treatment should be tailored to the severity and underlying cause of hyperkalemia

Common Pitfalls

1. Treating pseudohyperkalemia: Always confirm elevated potassium before initiating treatment
2. Ignoring hemolysis: Hemolyzed samples frequently cause falsely elevated potassium levels
3. Overlooking collection technique: Excessive muscle contraction and small-gauge needles can cause pseudohyperkalemia 1, 2
4. Missing underlying causes: Evaluate for renal dysfunction, medications, and other causes if true hyperkalemia is confirmed