A patient serum magnesium level came back at 2.4, but she’s not taking any magnesium-containing supplements. Are there other explanations for high magnesium level? Is there a normal upper limit? Can too much magnesium cause health problems?

Dr. Amy Nett:  Yeah, so absolutely. If you see high magnesium, a normal magnesium range, even from a conventional lab is going to be about 1.7 to 2.3 milligrams per deciliter. So 2.4 is an elevated magnesium level, especially for someone not taking supplements. So you should absolutely work this up a little bit more because the most common cause of an elevated magnesium level or hypomagnesemia is renal failure, so kidney disease. So you need to look at her kidney function markers a lot more closely. Other thing to think about, so you said she’s not doing magnesium supplementation, lithium therapy. So if she’s taking lithium, again we just mentioned like, well, I didn’t mention it, but lithium can be used for bipolar disorder. So if she’s taking lithium or has a psych issue and she’s on the relatively higher dose of lithium, that can cause decreased excretion of magnesium in the urine and so you’ll get high blood levels. Hypothyroidism can also cause hypomagnesemia, Addison’s disease. Again, we don’t see that too commonly. There’s familial hypocalciuric hypercalcemia—that one’s a mouthful—milk alkali syndrome, and they believe high magnesium has also been associated with depression as well. So a number of things that can cause high magnesium levels. So yes, 2.4 is a high magnesium level. In the absence of supplementation, even in the presence of supplementation, so that should be worked up further.