21/10/2025
🔆 Hyperkalemia
A potentially life-threatening electrolyte disturbance characterized by serum potassium > 5.0 mEq/L, leading to neuromuscular and cardiac complications.
📍 Cause / Pathophysiology:
• Impaired renal excretion: AKI, CKD, hypoaldosteronism.
• Increased potassium intake: excessive supplements, potassium-rich diet (rarely sole cause).
• Redistribution (shift out of cells): metabolic acidosis, rhabdomyolysis, burns, tumor lysis syndrome, hemolysis.
• Drugs: ACE inhibitors, ARBs, potassium-sparing diuretics, NSAIDs, heparin, trimethoprim.
• Pathophysiology: ↑ extracellular K⁺ → depolarized resting membrane potential → impaired muscle/nerve conduction + arrhythmias.
⌛ Epidemiology:
• Common in hospitalized & critically ill patients.
• High prevalence in CKD/dialysis patients.
• Medication-induced hyperkalemia is increasingly frequent in older adults.
📈 Clinical Features:
• Often asymptomatic if mild (K⁺ 5.0–5.5 mEq/L).
• Neuromuscular: weakness, fatigue, paresthesias, ascending paralysis (severe).
• Cardiac: palpitations, syncope, arrhythmias → sudden death.
• ECG changes (classic sequence):
– Tall, peaked T waves.
– Prolonged PR interval, flattened/absent P waves.
– Widened QRS → sine wave → VFib/Asystole.
📚 Investigations / Diagnosis:
• Serum potassium > 5.0 mEq/L.
• ECG: evaluate for cardiac effects.
• Renal function tests (BUN, Cr, eGFR).
• Arterial blood gas (check for metabolic acidosis).
• Rule out pseudohyperkalemia (hemolyzed sample, thrombocytosis, leukocytosis).
🚨 Clinical Importance:
• Hyperkalemia is a true emergency → can cause sudden cardiac arrest.
• ECG changes do not always correlate with severity → treat based on K⁺ level + risk factors.
• Requires rapid stabilization + definitive removal.
💊 Treatment / Management of Hyperkalemia
🔸 1. Stabilize Cardiac Membranes (if ECG changes or K⁺ ≥ 6.5 mEq/L):
• IV Calcium Gluconate: 10 mL of 10% solution IV over 2–5 min (onset 1–3 min, lasts 30–60 min).
• Alternative: Calcium chloride (more potent, but vesicant).
⚠️ Only protects myocardium – does NOT lower K⁺.
🔸 2. Shift Potassium into Cells (Temporary Measures):
• Insulin + Glucose: 10 units regular insulin IV + 25–50 g dextrose IV (lowers K⁺ by 0.5–1.2 mEq/L in 15–30 min).
• Nebulized β-agonist (Albuterol/Salbutamol): 10–20 mg via nebulizer over 10 min (lowers K⁺ by 0.5–1.5 mEq/L).
• Sodium Bicarbonate IV: 50 mEq IV over 5 min (especially if metabolic acidosis; less effective otherwise).
🔸 3. Remove Potassium from the Body (Definitive Measures):
• Loop Diuretics (Furosemide): if adequate renal function + euvolemia.
• Cation Exchange Resins (Sodium Polystyrene Sulfonate – Kayexalate): slow onset, not for emergencies.
• Hemodialysis: most effective & rapid; indicated in renal failure, refractory hyperkalemia, or life-threatening cases.
🔸 4. Prevent Recurrence:
• Stop offending agents (ACEi, ARB, spironolactone, NSAIDs).
• Restrict dietary potassium.
• Manage underlying cause (renal failure, acidosis, rhabdomyolysis).
• Regular monitoring in high-risk patients (CKD, dialysis).
📊 Key Facts (High-Yield):
• Hyperkalemia = K⁺ > 5.0 mEq/L; life-threatening if > 6.5 or with ECG changes.
• ECG: peaked T waves → wide QRS → sine wave.
• Calcium = first step if ECG changes (stabilizes heart).
• Insulin + Glucose = fastest temporary reduction.
• Dialysis = most definitive therapy.
• Always repeat K⁺ to rule out pseudohyperkalemia before initiating aggressive therapy.
