Dietary phosphorus is not an issue if you have healthy kidneys. However, if you suffer from advanced kidney disease, too much phosphorus can be a real problem. Dietary phosphorus doesn't hurt the kidneys, but it aggravates the biochemical imbalance common in people with advanced disease. Managing problems associated with phosphorus is a significant part of treating patients with advanced disease, including those on dialysis.
Normal Phosphorus Levels
Normal levels of serum phosphorus are between 3.5 to 5.5 mg/dL. These levels tend to creep up as chronic kidney disease progresses and the kidneys are less able to remove excess phosphorus from the blood. Nephrologists routinely measure serum phosphorus levels so that they can identify when this gets to be a problem.
High Phosphorus Levels
High phosphorus levels are a serious problem because phosphorus helps keep a healthy level of calcium in the bones and in the serum. When phosphorus levels get too high, the phosphorus leaches calcium from the bones. In addition to permanently weakening bones, high phosphorus increases the amount of calcium in the serum. When there is too much calcium in the serum, it creates deposits on the lungs, blood vessels, organs and muscles.
Treatment
Nephrologists treat high phosphorus levels by prescribing phosphorus binders and recommending a low-phosphorus diet. Phosphorus binders are a drug that patients take with meals. They bind to dietary phosphorus in the gut and cause it to be excreted before it can get in the bloodstream. The National Kidney Foundation recommends that patients with high phosphorus levels limit their intake of phosphorus to 800 to 1,000 mg per day.
High Phosphorus Foods
If you are on a low-phosphorus diet, using a phosphorus counter such as the one provided by the USDA is essential because food labels do not indicate how much phosphorus is in food. High phosphorus foods that need to be avoided or eaten very sparingly include beer, chocolate, cocoa, dark cola, dairy products, organ meats and dried beans and peas.
References
- National Kidney Foundation: KDOQI -- Guideline 4. Restriction of Dietary Phosphorus in Patients with CKD
- National Kidney Foundation: Phosphorus and Your CKD Diet
- DaVita: Phosphorus and Chronic Kidney Disease
- USDA National Nutrient Database: Search
- National Kidney Disease Education Program: Phosphorus - Tips for People with Chronic Kidney Disease
