Hyperkalemia

Hyperkalemia

David Ray Velez, MD

Definition: Serum Potassium (K) > 5.0-5.5 mEq/L

Severity

  • Mild: K > 5.0 without EKG Changes
  • Moderate: K > 6.0 or K > 5.0 with EKG Changes
  • Severe (Life-Threatening): K > 6.5 or K > 6.0 with EKG Changes

Causes

  • Pseudohyperkalemia – False Elevation Due to Blood Cell Rupture Associated with Blood Draw
  • Renal Failure
  • Adrenal Insufficiency (Addison’s Disease)
  • Crush Injury or Rhabdomyolysis
  • Tumor Lysis Syndrome
  • Significant GI Bleeding
  • Metabolic Acidosis
  • Diabetic Ketoacidosis (DKA)
  • Medications:
    • ACE Inhibitors
    • Beta Blockers
    • Succinylcholine
    • Excessive Potassium Supplementation

Presentation

  • Muscle Weakness or Paralysis
  • Cardiac Conduction Abnormalities
  • EKG Changes
  • *Clinical Manifestations Generally Do Not Occur Until After K ≥ 7.0 mEq/L

EKG Changes

  • Initial Findings:
    • Peaked T Waves
    • Shortened QT Interval
  • Later Findings:
    • Lengthening or PR Interval
    • Lengthening of QRS Complex

Treatment: Rapid Acting but Does Not Definitively Eliminate Potassium

  • IV Calcium
    • Effect: Stabilize Cardiomyocyte Membrane
    • Generally the First Medication Given
    • Dose: 1 g Calcium Chloride or Calcium Gluconate
  • Insulin and Glucose
    • Effect: Insulin Causes an Intracellular Potassium Shift and Glucose Prevents Resultant Hypoglycemia
    • 30-60 Minutes to Cause Effect
    • Dose:
      • 10 U Regular Insulin
      • 50 mL Dextrose 50% in Water (D50W) – 25 g Glucose
    • *Insulin is Given Alone if Serum Glucose > 250 mg/dL
    • Intracellular Shift Can Inhibit Clearance by Dialysis and Cause Rebound Hyperkalemia
  • Albuterol Nebulizer
    • Effect: β-Agonist Induces Intracellular Potassium Shift
    • 5-30 Minutes to Cause Effect

Treatment: Definitive Potassium Elimination

  • Oral Potassium Binders
    • Effect: Prevents Potassium Reabsorption in the GI Tract
    • Takes Hours to Effect (Not Used for Urgent Correction)
      • Oral Administration Takes > 6 Hours
      • Rectal Administration Takes 1-4 Hours
    • Sodium Polystyrene Sulfonate (Kayexalate) – Older Drug Falling Out of Favor Due to Risk of Bowel Necrosis
    • Sodium Zirconium Cyclosilicate (SZC/Lokelma) – Newer Drug Generally Preferred
  • Furosemide (Lasix)
    • Effect: Increased Potassium Excretion in Urine
  • Dialysis
    • Causes an Immediate Effect

Treatment Indications/Urgency

  • Indications for Emergent Treatment:
    • K > 6.5 mEq/L
    • K > 5.5 mEq/L with Renal Failure and Ongoing Tissue Breakdown (Rhabdomyolysis) or Potassium Absorption (GI Bleed)
    • EKG Changes
    • Symptomatic (Muscle Weakness or Paralysis)
  • Indications for Prompt Treatment (6-12 Hours):
    • K > 5.5 mEq/L and Marginal Renal Function
    • Need for Surgical Optimization
    • Dialysis Patients Outside of Regular Dialysis Timing
  • Most Patients with Mild-Moderate Hyperkalemia and No EKG Changes Do Not Require Urgent Correction and Can Be Managed by Dietary Modification and Management of Underlying Causes

Treatment Approach

  • Emergent Treatment: IV Calcium and Insulin/Dextrose for Rapid Correction
    • Consider Additional Therapy to Definitively Eliminate Potassium: Hemodialysis, Oral Potassium Binders, or Furosemide
  • Prompt Treatment (6-12 Hours): Does Not Require Rapid Correction with Calcium or Insulin/Dextrose
    • Prompt Therapy to Definitively Eliminate Potassium: Hemodialysis, Oral Potassium Binders, or Furosemide
  • Correct Any Underlying Causes
  • *Lactated Ringer (LR) is Preferred Over Normal Saline (NS)
    • Despite Potassium Content – Volume of Distribution is So Large that Any Effect is Essentially Negligible
    • NS Induces Hyperchloremic Metabolic Acidosis Which Worsens Hyperkalemia
    • En Vivo Studies Have Shown Lower Potassium Levels with LR than NS