A 50 year old woman complained of shortness of breath, but on closer questioning she seems to be weak.  An ECG was recorded immediately.  What is the diagnosis?

Answer below.

Notice large U-waves (arrows).  One is tempted to think that the long hump after the QRS (between the two vertical lines) is the T-wave.  Whenever you see this, you should think about both long QT and U-wave.  But if you look closely, you see there are 2 bumps, so the second one must be a U-wave.

The diagnosis of hypokalemia was made 1 hour prior to return of the lab value. K was 1.8.

This patient presented with hypotension, shock, acidosis, hgb of 8.  He stated he had been vomiting all day.

There is scooped ST depression in V4-V6, possibly due to ischemia, but mostly it is highly suspicious for hypokalemia.  The K was 2.6.