Recognising signs of danger: ECG changes resulting from an abnormal serum potassium concentration

A number of metabolic insults can result in changes to the serum potassium concentration. Potassium is predominantly an intracellular cation, and it has an important role in determining the resting membrane potential of cells. Disruption of the potassium gradient across the cell membrane can result in impaired cellular functioning. This may affect a number of organs including the cardiovascular and central nervous systems, resulting in various neurological symptoms and cardiac arrhythmias. Though laboratory tests are the gold standard test for diagnosing changes in the serum electrolyte concentration, there may be delays in obtaining the results. The electrocardiogram (ECG) may be a useful diagnostic tool, if the clinician is aware of the possible changes resulting from abnormalities in the serum potassium concentration. This article presents three cases that highlight the ECG changes resulting from an abnormal serum potassium concentration and will briefly look at the treatment options to reduce the risk of life threatening arrhythmias occurring.