<prompt> All are seen in Hypokalemia EXCEPT?U wave in ECGTall T wave in ECGST DepressionProlonged QU interval  <response>: Ans. b Tall T waves in ECGRef: Harrison 19th ed. 307,310 The earliest electrocardiogram ECG change associated with hypokalemia is a decrease in the T-wave amplitude. As potassium levels decline further, ST-segment depression and T-wave inversions are seen, while the PR interval can be prolonged along with an increase in the amplitude of the P wave. The U wave is described as a positive deflection after the T wave, often best seen in the mid-precordial leads eg, V2 and V3. When the U wave exceeds the T-wave amplitude, the serum potassium level is 3 mEqL. In severe hypokalemia, T- and U-wave fusion with giant U waves masking the smaller preceding T waves becomes apparent on the ECG. A pseudo-prolonged QT interval may be seen, which is actually the QU interval with an absent T wave.Severe hypokalemia can also cause a variety of tachyarrhythmias, including ventricular tachycardia fibrillation and rarely atrioventricular block. 