What is Hyperkalemia?

Hyperkalemia is serum potassium >5.0 mEq/L. It can cause life-threatening cardiac arrhythmias and requires urgent treatment when severe.

Symptoms:

• Mild-Moderate (5.0-6.5 mEq/L): Often asymptomatic
• Severe (>6.5 mEq/L):
  • Muscle weakness, paralysis
  • Cardiac arrhythmias → cardiac arrest
  • EKG: Tall peaked T waves, widened QRS, loss of P wave, sine wave pattern

Causes:

1. Increased Intake (Rare Alone):

• Potassium supplements, salt substitutes

2. Decreased Renal Excretion (Most Common):

• Chronic Kidney Disease (CKD/ESRD): Most common cause
• Adrenal Insufficiency: Low aldosterone → kidneys retain potassium
• Hypoaldosteronism (Type 4 RTA): Diabetes, CKD
• Medications:
  • ACE inhibitors, ARBs
  • Potassium-sparing diuretics (spironolactone, amiloride, triamterene)
  • NSAIDs
  • Trimethoprim, pentamidine
  • Heparin

3. Transcellular Shift (Potassium Moves Out of Cells):

• Acidosis (Metabolic or Respiratory)
• Insulin Deficiency (DKA)
• Tissue Breakdown: Rhabdomyolysis, tumor lysis syndrome, hemolysis
• Medications: Beta-blockers, digoxin toxicity, succinylcholine

4. Pseudohyperkalemia (Falsely Elevated):

• Hemolysis during blood draw (most common)
• Thrombocytosis, leukocytosis (K released from cells in tube)
• Clue: Repeat sample without tourniquet, free-flowing

Endocrine Causes:

• Adrenal Insufficiency (Addison's): Low aldosterone + low cortisol → hyperkalemia + hyponatremia
• DKA: Insulin deficiency + acidosis
• Hypoaldosteronism (Type 4 RTA): Common in diabetes + CKD

Diagnosis:

• Confirm True Hyperkalemia: Repeat sample (rule out pseudohyperkalemia)
• EKG: Assess for cardiac toxicity
• Review Medications
• Check: Creatinine (kidney function), blood glucose, acid-base status
• If Suspected Adrenal Insufficiency: AM cortisol, ACTH, renin, aldosterone

Treatment (Based on Severity):

Mild (5.0-5.9 mEq/L, No EKG Changes):

• Stop offending medications (ACEi, ARBs, K-sparing diuretics)
• Dietary potassium restriction
• Loop diuretics (if adequate kidney function)
• Sodium polystyrene sulfonate (Kayexalate®) or patiromer (Veltassa®)—GI K binders

Moderate-Severe (≥6.0 mEq/L or EKG Changes) - URGENT:

1. Calcium Gluconate (10%) 10-20 mL IV: Stabilizes cardiac membrane; FIRST-LINE if EKG changes
2. Shift K into Cells:
   • Insulin 10 units IV + dextrose (D50 25-50g) → lowers K by 0.5-1.5 mEq/L in 30 min
   • Albuterol nebulizer (10-20 mg)
   • Sodium bicarbonate (if metabolic acidosis)
3. Remove K from Body:
   • Loop diuretics (furosemide)
   • Dialysis (if severe, refractory, or ESRD)
   • GI K binders (slower onset)

Treat Underlying Cause:

• Adrenal insufficiency: Hydrocortisone, fludrocortisone
• DKA: Insulin, fluids