Definition and Diagnosis

• Hyperkalaemia is defined as a serum potassium concentration greater than 7mmol/l.
• Unfortunately, this is relatively common when capillary blood samples are haemolysed.  The first step should be to confirm a high serum potassium with a non-haemolysed venous or arterial sample.
• ECG changes (peaked T waves, or arrhythmias) indicate severe hyperkalaemia and require urgent treatment.

Aetiology

• The most important cause to investigate is oliguric renal failure.
• However, extremely premature babies may develop hyperkalaemia without significant renal impairment due to release of potassium from catabolised cells, as well as shift of intracellular potassium to the extracellular spaces.  This may be exacerbated by dehydration.

Complications

• In general, elevated potassium levels even above 7mmol/l are tolerated well by neonates.
• The main complication is arrhythmia, with the most common arrhythmias being ventricular tachycardia and sinus bradycardia. 

Treatment

1. Remove K from IV (i.e. hang 10% dextrose with Na⁺)
2. 10% Calcium Gluconate 0.5ml/kg IV (0.1mmol/kg)
3. Sodium bicarbonate 2mmols/kg IV given over 30 minutes.
4. IV 20% - 50% dextrose so blood glucose >12mmol/L.
   Then Insulin 0.3 unit/gram of glucose.
5. Resonium 0.5 - 1g/kg rectally.
6. Salbutamol 4micrograms/kg IV over 10 minutes ^3.  May be repeated after 2 hours.
7. Peritoneal dialysis.

References