Renal Diet Phosphorus Limits

Phosphorus is so common that deficiencies are almost unknown. More problematic for kidney patients are abnormally high serum levels of phosphorus, also called hyperphosphatemia. If you have high phosphorus levels, your nephrologist may recommend a low-phosphorus diet, and a drug called a phosphorus binder.

Kidney Disease

Nephrologists become more concerned about phosphorus levels in the later stages of kidney disease. There are five stages of kidney disease. People in stage 1 have evidence of kidney disease, but still have normal function. People in stage 2 have a glomerular filtration rate, or GFR, between 60 and 89 ml/min/1.73m2. The GFR for patients in stage 3 is 40 to 59, and for stage 4 is 15 to 29. People in stage 5 have a GFR less than 15. Maintaining healthy phosphorus levels is not usually a problem for patients in stages 1 and 2.

Importance

Serum phosphorus levels control how much calcium is in the bones and how much is in the blood. If serum phosphorus levels get too high, calcium is leached from the bone. This calcium ends up in the bloodstream, where it creates deposits on vascular tissue and muscle. Kidney patients can protect their bones and their cardiovascular system by preventing phosphorus levels from becoming elevated.

Adult Kidney Patients

Clinical Guidelines developed by the National Kidney Foundation state that patients in stages 3 and 4 should keep their phosphorus between 2.7 and 4.6 mg/dL. Recommendations for dialysis patients are slightly higher. These patients should try to keep their phosphorus levels between 3.0 to 5.5 mg/dL. Keeping phosphorus levels in this range will help keep serum calcium levels between 8.4 to 10.2 mg/dL.

Pediatric Kidney Patients

Recommended phosphorus levels for pediatric kidney patients are slightly different from adult levels. The National Kidney Foundation recommends that target serum phosphorus levels for adolescents on dialysis are between 3.5 and 5.5 mg/dL. Recommended levels for children under 12 are between 4 and 6 mg/dL.

Treatment

Phosphorus binders attach to phosphorus in your stomach and cause it to be excreted. They work best in patients who follow a low phosphorus diet and avoid organ meats, legumes, dairy products and other high phosphorus foods. If you take phosphorus binders, be sure to adjust the dosage if you consume a meal that contains more phosphorus than usual.