Which statement correctly describes Kayexalate’s mechanism for reducing potassium in hyperkalemia?

• A. It exchanges sodium for potassium in the colon, often causing diarrhea.
• B. It increases urinary potassium excretion.
• C. It blocks potassium absorption in the small intestine.
• D. It binds potassium in the bloodstream to lower serum levels.

Answer: (A)

The key idea is that Kayexalate lowers potassium by removing it through the gut, not by acting on the kidneys or bloodstream. Kayexalate is a sodium-filled resin placed in the colon where it exchanges sodium ions for potassium ions in the intestinal lumen. The bound potassium is then excreted in the stool, increasing fecal potassium loss and gradually reducing serum potassium. This is why diarrhea is a common side effect—the resin pulls water and electrolytes into the stool as it works.

It doesn’t raise potassium in the urine, so it’s not increasing urinary excretion. It also doesn’t act by blocking potassium absorption in the small intestine or by binding potassium in the bloodstream.