High phosphorus (hyperphosphatemia)
- Medically reviewed by
- AKF's Medical Advisory Committee
- Last updated
- December 12, 2022
Phosphorus is a mineral your body needs to work well. It is found in many foods and drinks and in certain medicines. Your body uses phosphorus, along with calcium and vitamin D, to keep your bones healthy and strong. However, too much phosphorus in your blood can harm your body.
The type of phosphorus in your blood is called phosphate. Your kidneys work to balance phosphate and other electrolytes in your blood, which help to balance the fluid levels in your body.
What is high phosphorus (hyperphosphatemia)?
High phosphorus, also called hyperphosphatemia, means you have extra phosphorus in your blood. High phosphorus is often a sign of kidney damage. For someone with healthy kidneys, the normal amount of phosphorus (phosphate) in the blood is between 2.5 to 4.5 mg/dL.
How is high phosphorus diagnosed?
To know if you have high phosphorus, doctors will test the phosphate level in your blood. If your phosphate level is higher than 4.5 mg/dL, your doctor may do other tests to check for kidney disease.
What are the symptoms of high phosphorus?
High phosphorus often does not cause symptoms itself. However, extra phosphorus in your blood can remove calcium from your bones and other parts of your body, leading to low calcium (also called hypocalcemia). Low calcium does cause symptoms, such as:
- Muscle cramps
- Bone and joint pain
- Weak bones
- Itchy skin or rash
As phosphorus removes the calcium from your bones, they become weak and unhealthy. This means you have a greater chance of broken bones and other problems.
Could I still have high phosphorus after a kidney transplant?
Yes, you can still have high phosphorus after you have a kidney transplant. This can happen for several reasons, such as:
- Damage to your bones from your kidney disease before the transplant
- Side effects of the medicines that stop your body from rejecting your new kidney (called immunosuppressants)
What causes high phosphorus?
High phosphorus is often a sign of kidney damage or disease. Healthy kidneys balance the phosphorus in your body by removing any extra phosphorus from your blood. If you have kidney disease, your kidneys may not remove extra phosphorus.
How do doctors treat high phosphorus?
The treatment for high phosphorus depends on what is causing phosphorus to build up in your blood. If you have CKD, talk with your doctor about what your phosphorus levels should be and whether you need to limit phosphorus in your foods, drinks or medicines.
If you are on dialysis, make sure you go to every dialysis treatment. Your doctor may also adjust how long or how often you get dialysis to remove extra phosphorus. You may also be prescribed phosphate binders, which are medications that lower the phosphate levels in your blood.
How can I prevent high phosphorus?
Talk with your doctor to find out how much phosphorus you should have and how you can prevent high phosphorus. Here are a few steps your doctor might recommend:
- Limit the phosphorus in your foods and drinks
- Take your medicines as your doctor prescribes
- Take a phosphate binder, a medicine that removes extra phosphorus in your body
- Take an over-the-counter calcium supplement
- Be active most days of the week, such as walking, biking or swimming
- Do not smoke or use tobacco
Eat these low phosphorus foods
- Italian, French or sourdough bread
- Corn or rice cereals and cream of wheat
- Unsalted popcorn
- Some light-colored sodas and lemonade
Avoid these high phosphorus foods
- Whole-grain bread
- Bran cereals and oatmeal
- Nuts and sunflower seeds
- Dark-colored colas
Questions to ask your nephrologist (kidney doctor) and dietitian:
When you are diagnosed with kidney disease, your nephrologist and dietitian will talk with you about managing your phosphorus.
Here are some questions you can bring to your appointment to ask your nephrologist:
- Do I need to worry about my phosphorus level at my stage of kidney disease?
- What should my phosphorus levels be?
- How often should I have my phosphorus levels checked?
- Do my blood test results show my phosphorus level at just that moment or over time?
- When should I start limiting the phosphorus in my meals?
- Should I take phosphate binders? If so, which kind and how should I take them?
- Would you recommend any other medicines?
- Can exercise help lower my phosphorus?
- Will dialysis remove any phosphorus?
- What happens if my phosphorus is not controlled? What symptoms should I look out for?
Questions to ask a dietitian:
- How much phosphorus do you recommend I eat every day and every week?
- How can I track the amount of phosphorus I eat?
- Where do I find phosphorus on a food label?
- When do I need to take my phosphate binders? Before, after or during meals?
- Are there any foods I should completely avoid?
- What is the difference between natural and added phosphorus? Is one type better than the other?
- Is there any way to remove or lower phosphorus in food?
- What should I do when eating out at a restaurant or somewhere else?
Resources for professionals
Take our free online continuing education (CE) course on Managing Hyperphosphatemia.
The goals of this course are to:
- Identify and understand the challenges dietitians and other allied health professionals face in managing hyperphosphatemia in their patients.
- Describe the different metabolism and impact of organic and inorganic phosphorus sources and identify food sources of both.
- Identify effective tools and strategies health professionals can employ in their own practice.
CE credits: 1.00 Commission on Dietetic Registration (CDR); 1.20 NANT; 1.00 Attendance