Magnesium

My senior texts me that we’re starting rounds at bedside of her patient, who just had a rapid called for SVT. They pushed amiodarone. She responded and converted. Crisis averted… for now.

Her magnesium is a little low this morning. Magnesium is commonly low in heart patients. It’s a side effect of one of the medications we use to keep the fluid burden on their heart low. They make a note to recheck and replace.

My mind flashes back to yesterday, which I was covering for my seniors patients on her day off. I got a call from the nurse about this same patient. “She’s having some pretty bad leg cramps.” The nurse said “we’ve already tried heating pads and the family is here at bedside rubbing them for her… Is there anything else we can try?”

“Hmm… Not off the top of my head, but let me look into it and get back to you.” I look it up. Mild stretching and warm compresses are recommended. Not much medication on top of that. I check her labs. Her magnesium is a little low. I look at the trends for this week. It’s been low before but they’ve been replacing it for her. I check a Cochrane review to see what evidence has to support leg cramps and magnesium treatment: Spoiler alert: it doesn’t. Still, the other day I myself had unprovoked, unexplained muscle cramps that felt like my muscles had been coated in PopRocks. Cured overnight by either a pill of magnesium supplement or a very powerful placebo effect. We’ll never know.

She needs mag anyway. I can be justified by giving it. She’s gotten it before and tolerated without issue. I take a deep breath and order 2 grams of IV magnesium; the smallest dose available. I head home for the evening and don’t think about it again.

“Last night she was having leg cramps and the cross cover doc ordered magnesium, which I thought was genius.” Said the nurse.

“Oh did that work?” I replied coyly. I couldn’t help myself. “Genius” is not the word people typically use when describing the contributions of an intern.

An anatomic win. But one I’ll remember for awhile.