This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
All are ECG changes in hypokalemia, except:U wave 
Select and explain. 
A. U wave, B. ST segment sagging, C. T-wave flattening or inversion, D. QT interval prolongation
D: QT interval prolongation
Answer: D: QT interval prolongation 
Explanation: Answer is D (QT Interval prolongation) Hvpokalemia may also present with a apparently prolonged QT interval on ECG. However this apparently prolonged QT interval is in reality the QU interval that mimics a prolonged QT interval due to fusion of T-U waves. Prolonged QT interval is the single best answer of exclusion. QT interval and 11% pokalemia Hypokalemia causes an 'apparent' prolongation of the QT interval but the real QT interval remains 'normal' The apparent prolongation of QT interval is due to fusion of the T and U waves (T-U fusion)