Introduction
Hyperkalemia is a condition where the serum or plasma potassium level is above the upper limits of normal, usually greater than 5.0 mEq/L to 5.5 mEq/L.
Actiology
- Hyperkalemia usually occurs as a result of potassium release from cells.
- Decreased renal excretion of K as in renal failure
- Decreased potassium secretion
- Impaired sodium reabsorption in
- Primary hypoaldosteronism
- Adrenal insufficiency
- Secondary hypoaldosteronism
- Medications such as ACE inhibitors, NSAIDs and heparin.
- Enhanced chloride reabsorption (chloride shunt) as seen in Gordon’s syndrome
Clinical features
- Weakness, flaccid paralysis, metabolic acidosis
- ECG changes
- Increased T wave amplitude
- Peaked T waves
- Prolonged PR intervals, QRS duration
- Atrioventricular conduction delays
- Loss of P waves
- Ventricular fibrillation or asystole
Investigations
- Serum Urea, Electrolytes and Creatinine
- Other renal function tests
- Acid base balance
Treatment objectives
- Correction of hyperkalaemia
- Preservation of cardiac function
- Treatment of underlying cause(s)
Management
This depends on the degree of hyperkalaemia, associated physical features and ECG changes
The measures are aimed at:
- Promoting potassium loss.
- Limiting exogenous potassium intake
- Discontinuation of anti-kaliuretic drugs
- Shifting potassium into cells
Drug treatment
Calcium gluconate
- 10 ml of 10% solution intravenously over 2-3 minutes
Insulin plus glucose infusion
- 10-20 units of regular insulin plus 25 – 50 g of glucose given as 10 units in 100 ml of 50% glucose
Other alternatives to cause influx of
potassium:
Sodium bicarbonate
- (134 mmoles/L) if there is metabolic acidosis See Cardiac Arrest
Or:
Parenteral/nebulised salbutamol (see
Bronchial asthma)
- Removal of potassium with diuretics (loop plus thiazide diuretics in combination)
- Sodium polysterene sulphonate (a cation exchange resin)
- Administered as a retention enema of 50g of resin and 50 ml of 70% sorbitol mixed in 150 ml of tap water
Haemodialysis
- The most rapid and effective way of lowering plasma potassium concentration
- Reserved for patients in renal failure
and those with severe hyperkalemia unresponsive to more conservative measures