Low magnesium levels in the cells (not just what can be found by a blood assay, but what the body has inside its cells) is called hypomagnesemia. It is seen more commonly these days in people who eat little shellfish, nuts, and green leafy vegetables grown in magnesium-poor soils. If it's too low in any one person, the chances of developing an arrhythmia rise. Apparently you checked out for potassium (hypo or hyperkalemia), but they found your magnesium levels out of range. It happened the other way around for me....I was given two potassium pills in the ICU for a wonky heart rhythm.

With some monitoring, and you taking maybe 400 mg of magnesium citrate or magnesium bis-glycinate, or magnesium malate....whatever is on sale and that you can tolerate safely on that daily dose, you should be fine. As always, run this past your family doctor, maybe with a view to having a blood assay for magnesemia every two months or so for a year. A year would make it a habit, one month not so much.....I mean the change in eating habits.

I am not an expert in this, and have no medical training. However, if your kidneys are healthy, no doctor has ever mentioned you have iffy kidney function, then they will excrete overages of both elements, potassium and magnesium. So, for a while at least, you are probably going to be safe taking 400 mg of magnesium daily....whichever form is on sale....and that doesn't cause you gastric upset or diarrhea. I know people who have to consume 1000 mg daily because their kidneys dump every bit of magnesium they encounter doing their blood filtration.