What is the purpose of phosphate binders in dialysis patients?

• A. To increase phosphorus absorption
• B. To bind phosphorus in the gut and limit absorption
• C. To remove phosphorus in urine
• D. To substitute phosphorus in the diet

Answer: (B)

Phosphate binders work by intercepting dietary phosphate in the gut so it isn’t absorbed into the bloodstream. In dialysis patients, kidney failure means phosphorus isn’t excreted effectively, so it can accumulate and cause bone and vascular problems. When binders are taken with meals, they latch onto phosphate in the intestine and form an insoluble complex that is removed in the stool, lowering serum phosphate levels. They aren’t about increasing absorption, removing phosphate in urine, or substituting dietary phosphate—their job is to prevent absorption of what you eat.