[mypalmike]

Blood tests are not particularly useful for detecting magnesium deficiency. Deficiency is in the cells, not the blood, and blood levels are fairly transient.

That said, it is definitely something to discuss with a doctor. I've had good luck recently working with a naturopath who is highly knowledgeable about nutrition and has far more time to discuss such things as diet and supplements than any general practitioner I've ever visited.