If you eat yourself, will you get hyperkalemic?
Sorry, let me rephrase:
Can upper GI bleeding cause hyperkalemia in predisposed people?
I feel like I’ve gotten that vibe from a couple patients. I can’t find any reports from others.. but I can think of a mechanism...
1/
Sorry, let me rephrase:
Can upper GI bleeding cause hyperkalemia in predisposed people?
I feel like I’ve gotten that vibe from a couple patients. I can’t find any reports from others.. but I can think of a mechanism...
1/
Blood contains a lot of protein.
When a significant amount of it is introduced into the proximal GI lumen (and some of it absorbed), it can elevate your BUN, or trigger hepatic encephalopathy.
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When a significant amount of it is introduced into the proximal GI lumen (and some of it absorbed), it can elevate your BUN, or trigger hepatic encephalopathy.
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The concentration of potassium in RBCs is ~100 mMol, meaning 100 mEq/L. If you start at a hematocrit of 40 and bleed 20% of your blood volume into your stomach...
That’s ~1 liter blood = 400 cc of red cells = 40 mEq of potassium.
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That’s ~1 liter blood = 400 cc of red cells = 40 mEq of potassium.
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You might say so what, I eat 4 bananas in one sitting, and I don’t get hyperkalemic.
Fair enough. Although do you?? And if you’re on an ACEi, don’t you??
But more importantly, there’s a difference between bananas and pure K+.
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Fair enough. Although do you?? And if you’re on an ACEi, don’t you??
But more importantly, there’s a difference between bananas and pure K+.
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40 mEq of K is actually a lot.
The total amount of potassium in our serum is only about 12 mEq (3L serum x 4 mEq per liter)!
By contrast, intracellular stores are MUCH higher: 50L cells x 100 mEq/L = 5000 mEq potassium.
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The total amount of potassium in our serum is only about 12 mEq (3L serum x 4 mEq per liter)!
By contrast, intracellular stores are MUCH higher: 50L cells x 100 mEq/L = 5000 mEq potassium.
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When we eat, the potassium in our food gets absorbed into the blood. Luckily, that potassium usually comes with carbohydrates (eg banana, potato, orange juice), which triggers insulin release, which puts the potassium into cells and keeps us from getting hyperkalemic.
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Does blood have enough carbohydrates in it to confer this protective effect? Maybe... maybe not. But even if we assume yes, there could still be an effect, especially since one can bleed more than a liter.
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If you bleed 2L/40% of your blood volume in a day, which isn’t unheard of - that’s 80mEq of potassium - and for someone with CKD, a subclinical RTA, on lisinopril... or an acutely depressed GFR from a brisk bleed... that might prove to be enough to raise serum levels.
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