Phosphorus is a mineral found in the body. About 85% of the phosphorus in the body is in bones. Phosphorus is the body’s next most abundant mineral after calcium. The body uses phosphorus to:
Phosphorus is absorbed in the small intestines and stored in the bones. Healthy kidneys get rid of the extra amounts not needed in the body. It is recommended that healthy adults get between 800 mg and 1,200 mg of phosphorus each day. A balanced, nutritious diet provides plenty of phosphorus, because it is found naturally in so many foods.
In addition, most Americans consume a lot of prepared foods, colas and other canned or bottled drinks, which have high amounts of added phosphorus. According to the Food and Nutrition Board, over the last 20 years, phosphorus intake by Americans has increased 10% to 15%. Part of this increase is attributed to phosphorus-containing food additives in processed food. It is very rare that people have a phosphorus deficiency; in most cases people get too much.
Phosphorus, calcium, vitamin D and parathyroid hormone and their interaction with the kidneys all play a part in controlling the level of phosphorus in the bloodstream.
Together, phosphorus and calcium create healthy bones and teeth. Healthy kidneys work to keep these two minerals in balance in the blood. The kidneys also turn vitamin D into an active hormone (calcitriol), which helps increase calcium absorption from the intestines into the blood.
When the calcium level in the blood is low, the parathyroid glands (four small glands in the neck) make more parathyroid hormone (PTH). This causes calcium to be pulled from the bone into the blood. Too much parathyroid hormone can cause the bones to become weak and break more easily. This is called renal osteodystrophy.
Because unhealthy kidneys are no longer able to remove phosphorus from the blood and get rid of the excess in urine, high levels of phosphorus (hyperphosphatemia) is a problem for people with stage 4 and 5 kidney disease, especially stage 5 (also known as end stage renal disease or ESRD).
High levels of phosphorus in the blood can cause:
People with kidney disease are urged to eat foods that are low in phosphorus. This will help keep the blood level of phosphorus in a healthy range.
One goal in treating people with end stage renal disease is to prevent phosphorus in the foods they eat from being absorbed into their bloodstream. To help with this, doctors prescribe medicines called phosphorus binders. In most cases doctors prescribe a binder to be taken along with meals and snacks that have phosphorus. Binders are like sponges that soak up phosphorus. Instead of going into the bloodstream, phosphorus stays in the stomach and then passes through the gastrointestinal system. A low phosphorus diet is necessary for phosphorus binders to work well.
Doctors may prescribe an active form of vitamin D, called calcitriol, to help balance the calcium and phosphorus levels. Active vitamin D cannot be taken if calcium or phosphorus levels are too high because it will increase the risk of phosphorus deposits in soft tissues such as arteries, lungs, eyes and skin.
A new medicine seems to help keep bones healthier in kidney disease patients. Called “calcimimetic” medication, it lowers PTH and calcium, and may even lower phosphorus. But it does not take the place of phosphorus binders. It’s still too early to know, but doctors hope this new drug will help kidney patients have healthier bones and lower the risk of calcifications and heart problems.
Dialysis treatments remove some phosphorus from the blood. It is important that the patient stay on dialysis for their full treatment time for best results. Between dialysis treatments, patients should be careful to limit how much phosphorus they eat.
Exercise can help increase physical strength and, in some case, even strengthen bones. Patients should ask their doctors to recommend an exercise program to help maintain their healthy bones and body.
To keep bone health, doctors will monitor their patients’ lab test results and adjust binders, medicines, supplements and dialysis treatments as necessary. In some cases, surgery to remove part of the parathyroid glands may be recommended to prevent long-term release of PTH. Patients should be sure to let their doctor and dietitian know all of the medicines and supplements they are taking because some of these may contain phosphorus. All of these efforts will help keep phosphorus in a healthy range, so that calcium will not be lost from the bones.
Treatment for high levels of phosphorus may include one or more of the following:
Patients can work with a renal dietitian and their doctors to keep their phosphorus and calcium levels in balance. Regular blood test will show the phosphorus and calcium levels in the blood. According to the “Clinical Practice Guidelines for Bone Metabolism and Disease in Chronic Kidney Disease” put out by the National Kidney Foundation, kidney disease patients in stages 3 and 4 should keep their phosphorus between 2.7 and 4.6 mg/dL. Dialysis patients should keep their phosphorus levels in the 3.0 to 5.5 mg/dL range or as close to the laboratory reference range as possible. The KDOQI goal for calcium is between 8.4 to 10.2 mg/dL.
Anyone who has ever tried to limit the amount of phosphorus they eat will tell you that almost every food has phosphorus. Knowing what to eat and how much is the key to keeping phosphorus levels in a good range. Nutrition Facts on food labels often do not give information on phosphorus. Because it is not listed does not mean the food is phosphorus free. Since food labels don’t list phosphorus, talking to a renal dietitian or using a nutritional reference guide will be help you learn the phosphorus content of most foods.
In many cases there are low phosphorus options for foods high in phosphorus. When limiting phosphorus in the diet, portion size is important. Resources such as food lists, grocery lists and recipes provided by the dietitian help you learn about phosphorus control. Visit the DaVita.com recipe section for renal-friendly meals and snacks that are low in phosphorus.
The renal dietitian is specially trained to help kidney patients make the best food choices. Each patient will be given individual guidance, taking into consideration their lab results, medical condition and food preferences. Make sure you consult with your dietitian and doctor about your situation. Below are some general tips to decrease your phosphorus intake.
If your doctor has prescribed phosphorus binders:
Note: The above list does not include all foods high in phosphorus. Portion size also plays a role in the amount of phosphorus you get from foods. Consult your dietitian and doctor to provide specific recommendations based on your individual needs.
Note: Even if food is considered low in phosphorus, portion size also plays a role in the amount of phosphorus you get from foods. Consult your dietitian and doctor to provide specific recommendations based on your individual needs.
This site is for informational purposes only and is not intended to be a substitute for medical advice from a physician.
Please check with a physician if you need a diagnosis and/or for treatments as well as information regarding your specific condition. If you are experiencing urgent medical conditions, call 9-1-1