Potassium replacement IV vs po

[confusedmedstudent22]

Hi there, quick question regarding IV vs po potassium replacement, like KCl. Tried looking it up but couldn't really see it anywhere. From my understanding, the main difference is whether you want to correct more quickly or not. Is there any efficacy difference between the two though, or is it 1:1 for po to IV? Thanks!

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[JJMrK]

You've got it. IV is faster and you can give it to patients that are NPO. 10 meqs should raise the K by about 0.1. You need a central line to run KCl quickly- running it through a peripheral takes an hour or more per 10 meqs and can cause infusion pain.

I typically give everyone PO unless there is a specific reason to give IV.

 

[Druggernaut]

Potassium is absorbed through the GI tract so effectively that it's just as quick to give it PO compared to IV. However, if someone was symptomatic and you really wanted to replace it quickly, you could give PO and IV simultaneously.

The rule of thumb for both is that 10 mEq will increase your serum potassium by 0.1.

 

[mmmcdowe]

I've always felt in my (perhaps more obese than average?) patient population that its 10mg IV for .1, or 30mg PO for .2 in the blood. Magnessium seems to be very strongly 10: 0.1 in both.

 

[mmmcdowe]

I think I was told by pharmacy that 60-80mg PO is the max oral dose that is absorbable. Pharmacy tells me many things though, like how IV acetaminophen is evil.

 

[Psai]

Heh. Pharmacy told me once that they had never seen an order for as much phos supplementation as the one I placed.

I was just like. Welp, you have now.

(It was a major liver resection patient who was burning through phos)

imagine how impressed they will be when the next guy tops your score

 

[J ROD]

From my experience, the PO takes longer and does not raise the level as much.

Many pharmacist can't think. They can just stay in the box. People are not boxes.

And, when giving K+ PO, I would recommend doing the 10mEq tabs. They are much easier to swallow for most patients and they don't mind taking an extra pill or 3 compared to the horse tabs or caps.

 

[Winged Scapula]

Despite the theoretic equivalence of oral vs IV, you definitely don't get the same level of a bump from PO potassium, at least in my anecdotal experience

Agreed - in addition I find that more than 30 mg PO is precursor to nausea.

 

[Raryn]

The other thing to keep in mind is that we usually way underdose the potassium. There's a fair bit of leeway on the 10meq=0.1 for both IV and PO, and people are afraid of giving enough.

The high end of normal for potassium is somewhere around 5.3-5.4 (depending on your lab), and unless you WAY overdo it, you're not getting anywhere close to that. Someone that's 3.0 should get at least 80meq (I usually do 40PO and 40 IV), because even if (jeebus forbid) it's twice as effective as the dogma, you still wont be above the low-mid 4s. Nowhere near a dangerous range. Half of my coresidents give 40 and then end up having to redose the patient daily. If I need to give more than 80, I'll usually increase the PO dose preferentially, because it's way faster than IV unless you have a CVC. 80meq PO can be given all at once (haven't had pharmacy blink at my orders) versus over 8 hours through and IV.

Also, if the patient isn't responding to potassium supplementation, gotta remember to check the Mg. Low Mg=refractory hypokalemia until you fix the underlying Mg problem.

(My record for K supplementation is ~1000 meq over 4 days between PO and IV. Patient had terrible DKA and required huge amounts to the point he was off his insulin drip half the time because we were worried about dropping his K any further. After we got him tanked back up and the acidosis resolved? Stable K for the remainder of the hospital stay).