This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fluid and electrolytes, Subject name: Medicine
In hypokalaemia all ECG changes are seen except 
Select and explain. 
A. Decreased T-wave amplitude, B. Normal ST segment, C. prolonged QT interval, D. U-wave
B: Normal ST segment
Answer: B: Normal ST segment 
Explanation: Electrocardiographic changes in hypokalemia include broad flat T waves, ST depression, u wave and QT prolongation. These are most marked when serum K+ is <2.7 mmol/L. (reference: harrisons principles of internal medicine,19E page-307)