If dialysate potassium concentration is set higher, what happens to potassium removal during dialysis?

• A. It reduces potassium removal
• B. It increases potassium removal
• C. It has no effect
• D. It only affects sodium

Answer: (A)

Potassium removal during dialysis is driven by diffusion across the dialyzer membrane, from the blood (higher potassium) to the dialysate (lower potassium). If you raise the potassium level in the dialysate, the concentration gradient shrinks, so less potassium diffuses out of the blood. In other words, increasing dialysate potassium reduces potassium removal.

This doesn’t mean there’s no effect at all—if the dialysate is set lower than the blood potassium, more potassium will be removed. The idea that only sodium is affected or that there’s no effect isn’t accurate; potassium removal is directly tied to the dialysate potassium concentration, with higher dialysate potassium reducing removal.