Hypokalemia and QT prolongation

[DocMiami]

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Can someone explain this relationship please.

With hypokalemia I would expect more potassium to move out of the cell, therefore, decreasing QT not increasing QT.

I looked at some sources online that stated Hypokalemia leads to less potassium to move outside the cell But WHY if there is a chemical gradient!!

 

[chromuffin]

Can someone explain this relationship please.

With hypokalemia I would expect more potassium to move out of the cell, therefore, decreasing QT not increasing QT.

I looked at some sources online that stated Hypokalemia leads to less potassium to move outside the cell But WHY if there is a chemical gradient!!

In hypokalemic states, you lose K+ overall. You're correct that K+ would move out of the cell down its concentration gradient in an effort to compensate. However, in hypokalemic states, even this compensatory K+ is lost. So you lose extracellular and intracellular K overall. But you lose extracellular more. That's the way I justify it. This increased loss of K+ will then result in an increased time necessary for sufficient K+ efflux and hyperpolarization (i.e. prolonged QT).