Dialysis is a medical procedure that removes waste products and excess fluid from the blood when a person’s kidneys are no longer able to perform this function adequately. While dialysis effectively filters many substances, certain dietary elements, such as phosphorus, can still build up in the body. To manage these accumulating substances, specific medications known as binders become a necessary part of treatment for individuals undergoing dialysis.
Why Binders are Needed in Dialysis
Individuals with kidney failure often experience hyperphosphatemia, a condition characterized by abnormally high levels of phosphorus in the blood. Healthy kidneys efficiently excrete excess phosphorus consumed through food, but impaired kidneys cannot perform this task effectively. Even with regular dialysis treatments, which remove some phosphorus, the amount of phosphorus absorbed from daily meals often exceeds what dialysis can eliminate, leading to its accumulation.
Sustained high phosphorus levels pose significant health risks for dialysis patients. These elevated levels can contribute to bone disease, weakening bones and increasing fracture risk over time. High phosphorus also plays a role in vascular calcification, where calcium deposits harden blood vessels, leading to serious cardiovascular issues. Managing phosphorus levels is an important aspect of long-term care for these patients.
How Binders Work
Binders function by interacting with dietary phosphorus directly within the digestive system. When taken with meals or snacks, these medications encounter phosphorus from food in the stomach and intestines. They chemically bind to the phosphorus, forming insoluble compounds that cannot be absorbed into the bloodstream.
This newly formed complex remains within the gastrointestinal tract and is subsequently passed out of the body through feces. By preventing phosphorus from entering the bloodstream in the first place, binders help to lower and control serum phosphorus levels.
Categories of Binders
One common type of binder includes calcium-based options, such as calcium acetate and calcium carbonate. These binders work by releasing calcium ions that combine with phosphorus in the gut to form insoluble calcium phosphate. While effective at reducing phosphorus absorption, a potential drawback is the risk of hypercalcemia, which is elevated calcium levels in the blood. This can contribute to soft tissue and vascular calcification if not carefully monitored.
Non-calcium-based binders offer an alternative, avoiding the addition of calcium to the body. Sevelamer, for instance, is a polymer that binds phosphorus through ion exchange and hydrogen bonding, forming a non-absorbable complex. Lanthanum carbonate operates by releasing lanthanum ions, which strongly bind to phosphate in the digestive tract. These non-calcium options are preferred for patients at risk of hypercalcemia or those with existing vascular calcification.
Iron-based binders represent another category, including compounds like sucroferric oxyhydroxide and ferric citrate. Sucroferric oxyhydroxide is an iron oxyhydroxide that binds phosphorus through ligand exchange in the gastrointestinal tract, forming insoluble iron phosphate. Ferric citrate not only binds phosphorus but can also help improve iron deficiency anemia, as some of the iron is absorbed. These binders offer distinct mechanisms and benefits.
Taking Binders and Common Side Effects
Binders are taken orally with meals or snacks to ensure they are present in the digestive tract when food phosphorus is consumed. Consistent adherence to the prescribed timing and dosage is important for their effectiveness in controlling phosphorus levels. Missing doses or taking them incorrectly can lead to higher phosphorus absorption and negate the benefits.
Patients using binders may experience various gastrointestinal side effects. Common issues include constipation, diarrhea, nausea, and indigestion. For instance, calcium-based binders are often associated with constipation, while sevelamer may cause more bloating or nausea.
Managing these side effects involves dietary adjustments, such as increasing fiber intake for constipation, or sometimes the use of prescribed laxatives. Patients are advised to discuss any side effects with their healthcare provider. A doctor or dietitian can offer personalized advice on managing discomfort and ensuring the continued effectiveness of phosphorus management.