Introduction

The normal range for the potassium concentration in serum is 3.8 to 4.9 mmol/L and in plasma is 3.4 to 4.5 mmol/L.¹

Common causes of hyperkalaemia are listed in Common causes of hyperkalaemia. To avoid inappropriate emergency treatment for hyperkalaemia, the abnormality should be confirmed on a serum sample without obvious haemolysis that has been centrifuged and analysed without delay. Delayed transfer of the sample to the laboratory, especially with cooling to 4 °C (which can provoke in vitro potassium release), is a common cause of pseudohyperkalaemia. In the primary care setting, samples taken later in the day are at particular risk of this effect. The artefact is aggravated by recentrifuging samples.

After confirming the diagnosis of hyperkalaemia, assessing acid–base and volume status and kidney function is essential for optimal choice of therapy. The most common cause is chronic kidney disease, followed by a depleted fluid volume. Hyperkalaemia management may require several options for therapy, depending on the clinical context and degree of urgency.

An ECG helps to assess how urgently treatment is needed. Urgent treatment is required if the ECG has changes due to hyperkalaemia (ie peaked T waves progressing to atrial arrest and a broadened QRS complex, indicating that ventricular arrest is likely to occur). This is unusual when the serum potassium concentration is lower than 7 mmol/L.