How does hypokalemia typically present on an ECG?

Hypokalemia typically presents on an ECG with a flattened T wave. This occurs because low levels of potassium in the blood can affect the repolarization phase of the cardiac action potential, leading to characteristic changes in the ECG waveform. The T wave reflects the repolarization of the ventricles, and when potassium levels are decreased, the shape of the T wave can be altered, often flattening or even becoming inverted.

It's important to note that while QT prolongation can be associated with other electrolyte imbalances or medication effects, it is not specifically indicative of hypokalemia. ST elevation usually suggests conditions like myocardial infarction rather than electrolyte disturbances. R wave inversion is generally linked with conditions such as ischemia or other structural heart issues, and is not a direct consequence of low potassium levels. Therefore, the flattened T wave serves as a more direct and reliable indicator of hypokalemia on an ECG.