High phosphorus (hyperphosphatemia)

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. Phosphorus is also used by your cells to produce energy. However, too much phosphorus in your blood can harm your body. 

Your kidneys work to balance phosphorus and other electrolytes in your blood. 

How is high phosphorus diagnosed? 

Having high phosphorus levels can be a symptom of chronic kidney disease. Your healthcare team will conduct different medical exams since there may not be any immediate symptoms of high phosphorus. These can include checking your medical history, conducting a general physical exam, discussing your food and fluid plan and reviewing your medicines with you. To determine if you have high phosphorus, your doctor will check the phosphorus levels in your blood, by taking a blood draw. Additional types of tests that your doctor may also check include urine protein test, ultrasound or kidney biopsy. If you are on dialysis, your healthcare team will likely check the phosphorus levels in your bloodregularly.   

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). When you have low calcium over time your bones become weak and unhealthy. This means you have a greater chance of broken bones and other problems, like osteoporosis (brittle bones). Having low calcium levels does cause symptoms, such as: 

• Muscle cramps 
• Bone and joint pain 
• Weak bones 
• Itchy skin or rash 
• Brittle nails 
• Dry skin 
• Coarser hair than normal  
• Irritability  
• Tingling in your lips, tongue, fingers or feet  
• Seizures 
• Abnormal heart rhythms (arrhythmia)  

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?

The main function of the kidneys is to filter waste out of your blood. When the kidneys are damaged these filters no longer work as well as they should or not at all if you have kidney failure. This can cause phosphorus to build up in your blood. 

Dialysis is a treatment to clean your blood when your kidneys are not able to. It helps your body to remove waste and extra fluids in your blood. It does some of the work that your kidneys did when they were healthy, like filter out extra phosphorus in your blood. While dialysis may help control phosphorus levels in your blood, it may not always be effective at keeping your phosphorus levels in a healthy range. The type of dialysis that you are receiving may also impact this. If you are getting in-center dialysis, typically 3 times a week versus home dialysis daily, your phosphorus levels may be controlled differently. With less frequent dialysis sessions, it is harder for dialysis to keep your phosphorus levels in a healthy range.  

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 chronic kidney disease (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. You may also be prescribed different medicines to help lower phosphorus levels in your body.  

Work with your healthcare team to find out the best treatment plan to keep your phosphorus levels in a healthy range.  

If you are not on dialysis, your doctor may first recommend that you limit the phosphorus that you are eating. You may work with a dietitian, who can help you with a low phosphorus food and fluid plan. If limiting the amount of phosphorus you eat does not work, your doctor will also recommend that you take a phosphate binder with your meals. This is a type of medicine that helps to manage your phosphorus levels.  

If you are on dialysis, your doctor may first recommend that you limit the phosphorus that you are eating. You may work with a dietitian to learn about different foods and drinks to choose more often and which ones to choose less often. If limiting the amount of phosphorus you eat while also receiving dialysis does not keep your phosphorus levels healthy, your doctor may recommend that you also take phosphate binders with your meals. In some cases, it may be difficult for individuals to keep their phosphorus levels at a healthy range when they are on dialysis and taking phosphate binders. Your doctor may consider adding a phosphate blocker. This is a newer medicine to help keep phosphorus levels healthy for individuals on dialysis when phosphate binders are not working well enough.  

• Phosphate binders help to prevent excess phosphorus from the food you eat from getting into your body. These medicines are used to help individuals with chronic kidney disease better manage their phosphorus levels and are taken every time you eat. Phosphate binders work by soaking up phosphorus in the stomach, similar to a sponge soaking up water to help your body get rid of it.   
• Phosphate blockers are used when phosphate binders are not working well enough to get phosphorus levels to a healthy range. Phosphate blockers also help to remove excess phosphorus from the food you eat from getting into your body. This type of medicine works by acting as a roadblock, to block phosphorus from getting into your bloodstream. This medicine is typically taken in the morning and at night, as opposed to phosphate binders that are taken with every meal.  
• Talk to your healthcare team about what type of phosphate-lowering medicines may be best for you. Keeping phosphorus levels in the body at healthy levels may be challenging. Following a treatment plan with medicine and food and fluids low in phosphorus can help you better control your phosphorus levels.