What is the mechanism by which insulin treats hyperkalemia?

Answer 1

A really good question!

Hyperkalemia makes the cardiac muscles unhappy and leads to cardiac arrest (VTach leads to Vfib which leads to Vdeath). However the cardiac muscles are only unhappy if they can see the potassium floating around in the blood. So if serum potassium is high, we don't want the heart to be sad, we really have 2 options:

1. Get the potassium out of the body (options will include diuretics to excrete the potassium in urine or something like Polystyrene sulfonate aka kayexalate which sends the potassium out with feces
2. HIDE the potassium inside the bodies cells.

Inuslin does option #2. It doesn't actually decrease the potassium molecules in the body --- rather it drives the potassium into the cells so that potassium is no longer swimming around freely in the serum. The heart is happy, the person is happy and everyone wins.

JUST REMEMBER to give glucose with that insulin or else the person won't be happy. And we really don't want that.

Answer 2

Great question!

Insulin leads to increased Na–K-ATPase activity (the sodium-potassium pump), which is an enzyme that classically transports 3 sodium ions out of the cell, and 2 potassium ions into the cell, for each ATP hydrolyzed.

Because of this, increasing insulin levels lead to a shift of potassium ions (K+) from the extracellular space to the intracellular space, which causes a reduction of the potassium concentration in the blood and is how insulin can reduce hyperkalemia.