Hyperkalemia

Background

• Serum potassium above 5mmol/L

Pathophysiology

• 98% of total body potassium is intracellular
• Gradient maintained by
  • Na-K antiporters (3Na:2K)
  • H-K antiporter
• Normally excreted in the urine
  • Aldosterone stimulates ENAC channels and Na-K channels

Clinical Manifestations

• Arrythmias
  • Bradycardia
  • Asystole
• Muscle paralysis (tetany)

Differential Diagnosis

• Decreased excretion
  • Decreased aldosterone
    • Primary adrenal insufficiency
    • Secondary adrenal insufficiency
      • ACE inhibitors
      • Angiotensin receptor blockers
      • Renin inhibitors
      • NSAIDs
      • Congenital adrenal hyperplasia
  • Decreased aldosterone responsiveness
    • Spironolactone
    • Amiloride
  • Decreased sodium delivery to kidneys
    • Hypovolemia
    • Heart failure
    • Cirrhosis
    • Nephrotic syndrome
• Increased intake
  • Iatrogenic
• Shifts
  • Rhabdomyolysis
  • Tumour lysis syndrome
  • Acidosis
  • Drugs
    • Hypoinsulinemia
    • Beta blockers
    • Digoxin
    • Succinylcholine
  • Hemolysis
  • Anemia
  • Increased plasma osmolality
• Factitious
  • Hemolysed samples
  • Increased white cell count
    • Chronic lymphocytic leukemia
  • Increased platelets

Management

• EKG
• Repeat serum potassium
• Pharmacologic treatment indicated if EKG changes
• Stabilize
  • Calcium gluconate 1g IV push q30min prn EKG changes
    • Lasts 30-60 minutes
    • Repeat EKG in 30 minutes, then can give another 1g
• Shift
  • Insulin R 10 unites in 1 amp D50W
  • Albuterol 8-10 puffs
  • Bicarbonate
    • No evidence of benefit and increases serum sodium
• Excrete
  • Kayexalate and lactulose
    • Takes 2-3 days to work
  • Normal saline
  • If not hypovolemic and not on ACEi or ARB, furosemide
  • If refractory to medical management, dialysis