Hyperkalemia is defined as a serum potassium concentration greater than 5.5 mmol/L.
Etiology
The main causes include:
- Excessive potassium intake, such as from consuming potassium-containing medications, excessive intravenous potassium administration, or transfusion of stored blood with prolonged storage times.
- Reduced renal potassium excretion, as seen in acute or chronic renal failure, use of potassium-sparing diuretics, such as spironolactone or amiloride, and adrenal insufficiency.
- Potassium release from cells, such as in cases of hemolysis, tissue damage, or acidosis.
Clinical Manifestations
Patients may present with mild muscle tremors, paresthesia in the hands and feet, limb weakness, diminished or absent tendon reflexes, and even flaccid paralysis. Cardiac complications include sinus bradycardia, atrioventricular conduction block, rapid arrhythmias, ventricular fibrillation, or cardiac arrest.
Characteristic electrocardiogram (ECG) changes in hyperkalemia include tall, peaked T waves, shortened QT intervals, widened QRS complexes with reduced amplitude, and decreased amplitude or disappearance of P waves.
Diagnosis
Individuals with underlying conditions that could cause hyperkalemia who display the clinical manifestations described above, which cannot be attributed solely to their primary disease, should be considered for potential hyperkalemia. Hyperkalemia can be confirmed when serum potassium concentration exceeds 5.5 mmol/L. ECG findings provide valuable diagnostic support.
Treatment
Once hyperkalemia is diagnosed, discontinuation of all potassium-containing medications or solutions is essential. Concurrently, the following measures are used to reduce serum potassium levels:
Promoting the intracellular shift of potassium
The methods include:
- Administering 10–20 ml of 10% calcium gluconate solution by slow intravenous injection after dilution, which acts rapidly but has a short duration of effect.
- Infusing 250 ml of 5% sodium bicarbonate solution intravenously, which can increase blood volume to dilute serum potassium, promote potassium movement into cells or excretion through urine, and help correct acidosis.
- Infusing 10 units of insulin in 300–500 ml of 10% glucose solution over one hour, which typically lowers serum potassium by 0.5–1.2 mmol/L.
Diuretics
Loop diuretics, such as 40–100 mg of furosemide, or thiazide diuretics are commonly used to promote renal potassium excretion. However, these drugs may have limited efficacy in patients with renal dysfunction.
Cation Exchange Resins
Polystyrene sulfonate (potassium-lowering resin) can be administered orally at a dose of 15 g, 2–3 times daily. For patients unable to take it orally, it can be given via enema to promote potassium excretion through the gastrointestinal tract.
Dialysis Therapy
Blood dialysis and peritoneal dialysis are the most effective and rapid methods for reducing serum potassium levels. Hemodialysis clears potassium at a much faster rate than peritoneal dialysis and is indicated for patients with severe hyperkalemia or those refractory to other treatments.