What doctors don't know is that really low magnesium will also impact the heart. Especially if you use certain drugs that are know to prolong QT...

Potassium AND magnesium are very important!

This link is to the most complete information on the subject of prolonged QT potential:
http://www.azcert.org/index.cfm

http://www.chfpatients.com/stew/minerals.htm
too low magnesium level prevents potassium from entering cells. They work together!

Its a difficult thing, because too much magnesium can make our MG worse, I may have to do some study if they know just how much is too much.......

I understand that, redtail.

I am talking about depletions, which can be severe.
I never recommend large doses of magnesium for anyone.
But you do need some to function properly.

High doses may be used in pregnant women who have eclampsia, or patients who present in the ER with severe deficiency causing cardiac arrhythmias.

Keeping magnesium within normal limits would avoid large dose scenarios which would have a negative impact on MG patients.