Potassium abnormalities

Cite this article as:
Tessa Davis. Potassium abnormalities, Don't Forget the Bubbles, 2014. Available at:


K + < 2.5 mmol/L:

  • Prominent U wave develops with apparent prolongation of the QTc
  • Flat or diphasic T waves
  • ST segment depression

As K + falls further:

  • PR interval prolongs
  • Sinoatrial block may occur



As K + rises:

  • Tall peaked T waves, best seen in precordial leads
  • Prolongation of QRS duration
  • Prolongation of PR interval
  • Disappearance of P waves
  • Wide bizarre diphasic QRS complexes (sine waves)
  • Eventual asystole


potassium and ecgs