Evidence for repleting electrolytes

[CopperStripes]

It seems like a significant portion of intern year is writing orders for K, Mg, and Phos in patients with only marginally low values of these electrolytes. Potassium especially - I'm often told to give K when the value is between 3.5 and 4, though this is considered a normal range. I'm wondering if there is any literature out there demonstrating when it is actually advantageous to replete electrolytes. Of course I don't want to wait until there are EKG changes... but it is really necessary to "correct" electrolytes that are hardly abnormal?

Thanks for your help.

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[jdh71]

It seems like a significant portion of intern year is writing orders for K, Mg, and Phos in patients with only marginally low values of these electrolytes. Potassium especially - I'm often told to give K when the value is between 3.5 and 4, though this is considered a normal range. I'm wondering if there is any literature out there demonstrating when it is actually advantageous to replete electrolytes. Of course I don't want to wait until there are EKG changes... but it is really necessary to "correct" electrolytes that are hardly abnormal?

Thanks for your help.

I've often wondered the same thing. You know there are people just wondeirng around out in the community with K's of 3.0 and 6.0 and they simply aren't falling over dead from arrhythmia. Mg almost ALWAYS gets correct wrong (it's an intracellular cat, if it's low in the serum, total body is low - needs more than 2 grams). Phos is important on vented patients, but patients that are eating almost never need IV replacement.

The problem is, that it's standard community practice to replace these lytes, and if god forbid something were to happen, you can bet a lawyer will jump all over your ignoring a K of 3.4

 

[Rendar5]

I'm not as concerned by low K+ as I am of high K+. In the ER, unless someone's at or under 3, I just tell them to eat bananas if they're being d/c'd, and give them maybe 20meq (not enough to hit 3.5, but enough to get them in the right direction). For the 3.5-4.0 range, I just let internal medicine deal with it if they're being admitted. Hyperkalemia I always treat in some way over 5.0 because it can go from no EKG changes to bad EKG changes anytime it wants to. The only except for my ED pt's is borderline hyperK+'s that I have a clear cause for that can be easily adjusted on d/c (i.e., they're taking K-Dur 20 with their lasix and are not in renal failure).

 

[Buzz Me]

Mg almost ALWAYS gets correct wrong (it's an intracellular cat, if it's low in the serum, total body is low - needs more than 2 grams). Phos is important on vented patients, but patients that are eating almost never need IV replacement.

(1) Who's out there giving less than 4 g mag sulfate? 😕
(2) Watch out for plummeting phos levels in a hepatectomy patient POD #3-4.

 

[Instatewaiter]

It seems like a significant portion of intern year is writing orders for K, Mg, and Phos in patients with only marginally low values of these electrolytes. Potassium especially - I'm often told to give K when the value is between 3.5 and 4, though this is considered a normal range. I'm wondering if there is any literature out there demonstrating when it is actually advantageous to replete electrolytes. Of course I don't want to wait until there are EKG changes... but it is really necessary to "correct" electrolytes that are hardly abnormal?

Thanks for your help.

Our renal docs love to rip on us when we have a cards patient and have K goals of 4 and Mg goals of 2 because there really isn't any evidence according to them. I haven't looked it up. The K kinda makes sense if you are diuresing them and they could rapidly lose K but the Mg goal doesn't make all that much sense.

I'd love to see the evidence but quite frankly I am way too lazy to look it up.

 

[docB]

Here's and old thread that talks about this. There's a link in there for an 80s article call "Fending off the Potassium Pushers." It had no abstract so you have to look for it.

 

[jdh71]

(1) Who's out there giving less than 4 g mag sulfate? 😕

You might be surprised (no, you wouldn't)

 

[ASA6]

(1) Who's out there giving less than 4 g mag sulfate? 😕
(2) Watch out for plummeting phos levels in a hepatectomy patient POD #3-4.

actually, when I was an intern, I had a nurse refuse my order for 4 gm of mag, she said it was too much. The pts mag was like 1.1. I had to have my resident and the pharmacist talk to the nurse manager (the charge nurse refused to) before they would ok the order.