Hypernatraemia induced by sodium polystyrene sulphonate (Kayexalate®) in two extremely low birth weight newborns

Hyperkalaemia is a life-threatening electrolyte disorder that can occur in the first week of life in almost 50% of preterm infants with a birth weight less than 1000 g [extremely low birth weight (ELBW)]. Serum potassium values higher than 7 mmol·l-1 are associated with cardiac arrhythmias and an increased incidence of intraventricular haemorrhage and periventricular leucomalacia. Therapeutic options to treat this dangerous imbalance comprise calcium gluconate, insulin plus glucose, albuterol/ salbutamol inhalation. Administration of cation-exchange resin such as sodium polystyrene sulphonate (Kayexalate®) is effective in lowering plasma potassium, although complications following oral or rectal administration are reported in newborns. We describe two ELBW infants affected by hyperkalaemia, treated with Kayexalate, who developed serious hypernatraemia, that has never been reported before in preterm infants.