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Hypokalemia Emergency Management

Failure to treat the magnesium deficiency will make it difficult or impossible to fix the hypokalemia (hypomagnesemia causes renal potassium-wasting, so the patient will keep on spilling potassium until their magnesium level is repleted).

Magnesium repletion is also useful because it will reduce the risk of Torsade de pointes in these patients.

Magnesium can be replaced rapidly (faster than potassium). This may be the fastest approach to decrease the patient’s risk of arrhythmia.

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 Replace/Correct the Magnesium Deficiency Before Potassium (Hypokalemia)!

Let’s wrap it up. Potassium cannot go from plasma into the cells of the kidney unless the Na-K-ATPase channel is working. Magnesium helps this channel work. So if you don’t have enough magnesium, you can do whatever you want but the Na-K-ATPase pump isn’t going to properly. At the same time the intracellular concentration of potassium is going to remain low. Why exactly? It is not described. Quite frustrating really.

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Hypomagnesemia

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Most patients who are hypokalemic are hypomagnesemic and require magnesium supplementation. Checking a level is unnecessary.

Shockingly Dangerous Hypokalemia

Potassium chloride (KCl) is the preferred choice for IV repletion as it has faster onset than potassium bicarbonate. KCl should be administered in an isotonic saline solution without dextrose. The use of dextrose-containing fluids will prompt an insulin release, driving potassium into the cells resulting in further reduction of serum potassium levels.

Resources

CORE EM

Severe hypokalemia can lead to lethal dysrhythmias typically by prolongation of the QT interval.

EMCrit

Failure to treat the magnesium deficiency will make it difficult or impossible to fix the hypokalemia (hypomagnesemia causes renal potassium-wasting, so the patient will keep on spilling potassium until their magnesium level is repleted).