I respectfully disagree. We lose a ton of K and Mg with the diarrhea, and that makes us feel weaker. Don’t need blood tests; if your kidneys are normal, your body can handle the K and Mg you need. If your kidneys are NOT healthy, that’s the only time K becomes an issue; you pee out what you don’t need otherwise, just like excess B and C vitamins, sodium, and all the other stuff we ingest that isn’t in perfect harmony with our body’s needs of the moment.
I say this as a recently retired MD who manages her own electrolyte issues so as to avoid the ER, despite a short gut and 20-30x bms/day on meds.
Dehydration is a part of it, but water and sports drinks won’t fix it if you have significant diarrhea still. Orange juice, bananas, leafy greens (if you can tolerate them) are good for K; Mg is equally important, as it’s what keeps your muscles from cramping, among many other things. Mg highest in nuts (which are hard for many of us w IBD/pouches to tolerate), and oysters, but supplements can help.
Word of caution: you probably don’t want a Magnesium Oxide supplement—which means most of the ones in the drugstore. Mag sulfate bad, too. Both are used to treat constipation, so they won’t be helpful for diarrhea-induced Mg loss—can make it worse.
There is a form available on Amazon called magnesium taurate; it is one of the only formulations I’ve found that doesn’t worsen diarrhea. It’s a giant horse pill, unfortunately, but I crush it to help absorption.
Potassium tastes pretty bitter and nasty, so I’ve found electrolyte mix packets highest in K and Mg to taste gross on their own. Just add lemon juice or a nice tube of crystal light, or whatever you feel like, and it’s drinkable.
Please, please be careful about electrolyte loss. If drinking water doesn’t make you feel better, you will want to supplement yours. It is safe; these are all sold without prescription and are USP grade. And don’t forget, you lose sodium, too. It’s not a bad idea to have a bit of sodium added to the drink if your diet doesn’t already contain much.
When I’m low on sodium, I feel nauseous, with a bad headache and brain fog. If I don’t head it off quickly, I vomit, and can’t stop. It’s ugly. Now I recognize that feeling and eat something salty or drink pickle juice or chicken broth; has kept me out of the ER more than once.
Low K and Mg are more that feeling of weakness, the spent feeling after a bad day of runs. Muscles don’t contract well without Mg, and nothing works as well when K is low. I know when my body is feeling worse than usual that I need to load up. It definitely helps; keeping electrolyte packets on hand and the Mg tablets has stopped me from having terrible cramps in hands, feet, calves bc of diarrhea.
Good luck! It’s not all dehydration—you really are losing precious electrolytes that normally would get resorbed into the bloodstream with the water... the colon had an important job, conserving water loss and electrolytes, concentrating wastes for expulsion. That’s the only reason ‘normal’ stools are solid; reabsorption of water content. Over time as small bowel adapts, it gets better at compensating, but it depends on how much small bowel you have left. That’s how antidiarrheals like lomotil and imodium work; they slow down the motility of the intestine, giving the body time to absorb more water from the stools. More water in stools equals more diarrhea, and more urgency.