Electrolyte and acid–base disorders in AKI

Electrolyte disturbances are common in patients with acute kidney injury (AKI) and should be corrected. In particular, hyperkalaemia above 6–6.5 mmol/L (especially with electrocardiogram changes) constitutes a medical emergency and warrants immediate intervention. Both hypo- and hypernatraemia may occur during AKI. Chronic changes in serum sodium need to be corrected bearing in mind the underlying pathology; however, when severe and evolving rapidly they should be corrected faster, irrespective of the cause. Acid–base disorders are also common in AKI and need to be treated in the context of underlying problems and physiological compensatory mechanisms. In metabolic acidosis, a bicarbonate deficit may be corrected by sodium bicarbonate administration. Of note, whilst patients with AKI tend to retain electrolytes such as potassium and phosphate, this might be reversed during renal replacement therapy and even substitution of these losses may be required.