What is the oral or rectal medication given to reduce potassium levels?

Sodium polystyrene sulfonate, commonly known as Kayexalate, is the medication used to reduce elevated potassium levels in the body, a condition known as hyperkalemia. It works by exchanging sodium ions for potassium ions in the intestinal tract. As a result, potassium is expelled through the feces. This mechanism makes it particularly effective in lowering potassium levels when hyperkalemia is present, especially in patients with conditions such as chronic kidney disease, where potassium excretion is impaired.

Other options such as calcium carbonate and furosemide do not specifically target potassium levels. Calcium carbonate is often used for calcium supplementation and does not have a direct role in potassium reduction. Furosemide, a loop diuretic, can help lower potassium indirectly through increased urine production but is not primarily used for this purpose. Spironolactone, being a potassium-sparing diuretic, actually retains potassium rather than reducing it. Therefore, the specific action of sodium polystyrene sulfonate towards potassium excretion makes it the correct answer for reducing potassium levels.