Kidney Failure Risk Factor: Serum Phosphorus

Phosphorus is an important mineral that's found in many foods. After we eat it, phosphorus goes mostly to our bones. We need to get phosphorus in the diet because our bodies can't make it.

Along with calcium, phosphorus is needed to build healthy bones and teeth. The remaining phosphorus is found throughout our bodies, where it is used to give us energy. This energy is very important for good muscle function, including the muscles that help us breathe.

Serum phosphorus is the phosphorus in our blood.

Healthy kidneys can remove extra phosphorus in your blood. But when you have chronic kidney disease (CKD), your kidneys can't remove phosphorus very well. Extra phosphorus causes body changes that pull calcium out of your bones, making them weak.

High phosphorus can also combine with calcium, leading to dangerous deposits in the blood vessels, lungs, eyes, and heart. Over time this can cause an increased risk for heart attack, stroke, or death.

Aside from these dangerous effects, studies have also shown that high phosphorus levels may directly harm the kidneys and cause a loss of kidney function. This loss of function increases the risk for kidney failure.

A normal serum phosphorus level is 2.5 to 4.5 mg/dL. Even if you have CKD, there are reasons why your phosphorus level may be too low, and you may need treatment for that. But in general, most CKD patients need to control their phosphorus level. Keep track of your phosphorus levels and discuss them with your healthcare team.

You can keep your serum phosphorus level normal through diet and medicine. A dietitian who works with kidney patients can help you plan a low phosphorus diet that fits your individual needs. Below are some basic facts about phosphorus in food.

Organic phosphorus is found naturally in many unprocessed protein-rich foods such as meats, poultry, fish, nuts, beans and dairy products. But the phosphorus in animal foods is absorbed more easily than the phosphorus in plant foods. Therefore, eating more plant-based protein like soy rather than animal-based protein like meat may be helpful in limiting your phosphorus intake.

Inorganic phosphorus that has been added to food as an additive or preservative is found in fast foods, ready-to-eat foods, canned and bottled drinks, enhanced meats, and most processed foods. Inorganic phosphorus is completely absorbed. Therefore, avoiding phosphorus additives can greatly lower your phosphorus intake. Phosphorus additives are listed on the nutrition facts label under "ingredients." Look for "PHOS" to find phosphorus additives in packaged foods.

Phosphorus additives found in foods include:

• Dicalcium phosphate
• Disodium phosphate
• Monosodium phosphate
• Phosphoric acid
• Sodium hexameta-phosphate
• Trisodium phosphate
• Sodium tripolyphosphate
• Tetrasodium pyrophosphate

Your healthcare team may order a medicine called a phosphate binder for you to take with meals and snacks. This medicine will help control the amount of phosphorus your body absorbs from the foods you eat.

There are different types of phosphate binders. Pills, chewable tablets, powders, and liquids are available. Some types also have calcium, while others do not. You should only take the phosphate binder that is ordered by your healthcare team.

For more information:

• Speak with your healthcare team
• Visit the National Kidney Foundation at www.kidney.org