Having a high level of phosphate — or phosphorous — in your blood is known as hyperphosphatemia. Phosphate is an electrolyte, which is an electrically charged substance that contains the mineral phosphorous.
Your body needs some phosphate to strengthen your bones and teeth, produce energy, and build cell membranes. Yet in larger-than-normal amounts, phosphate can cause bone and muscle problems and increase your risk for heart attacks and strokes.
Most people with high phosphate levels don’t have symptoms. In some people with chronic kidney disease, high phosphate levels cause calcium levels in the blood to drop.
Symptoms of low calcium include:
- muscle cramps or spasms
- numbness and tingling around the mouth
- bone and joint pain
- weak bones
- itchy skin
Most people get about 800 to 1,200 milligrams (mg) of phosphorous daily from foods like red meat, dairy, chicken, fish, and fortified cereal. In the body, phosphate is found in the bones and teeth, inside the cells, and in much smaller amounts in the blood.
Your kidneys help remove extra phosphate from your body to keep the levels in balance. When your kidneys are damaged, your body can’t remove phosphate from your blood quickly enough. This can lead to chronically elevated levels of phosphate.
Your blood phosphate level can also rise abruptly if you receive a phosphorous-containing laxative as preparation for a colonoscopy.
Other possible causes of hyperphosphatemia include:
- low parathyroid hormone levels (hypoparathyroidism)
- damage to cells
- high vitamin D levels
- diabetic ketoacidosis — high levels of acids called ketones in the blood of people with diabetes
- injuries — including those that cause muscle damage
- serious body-wide infections
Calcium combines with phosphate, which leads to low levels of calcium in the blood (hypocalcemia). Low calcium in the blood increases your risks for:
- high parathyroid hormone levels (secondary hyperparathyroidism)
- bone disease called renal osteodystrophy
Because of these complications, people with severe kidney disease who have high phosphate levels in their blood face an increased risk of dying.
Your doctor can do a blood test to check whether you have high phosphate levels.
If your kidneys are damaged, you can lower high blood phosphate levels in three ways:
- reduce the amount of phosphate in your diet
- remove extra phosphate with dialysis
- lower the amount of phosphate your intestines absorb using medicine
First, limit foods that are high in phosphorous, such as:
- red meat
- chicken and other types of poultry
- egg yolks
Diet alone probably won’t lower your phosphate levels enough to fix the problem. You may also need dialysis. This treatment takes over for your damaged kidneys. It removes wastes, salt, extra water, and chemicals like phosphate from your blood.
In addition to diet and dialysis, you’ll probably need medicine to help your body remove excess phosphate. A few drugs help reduce the amount of phosphate your intestines absorb from foods you eat. These include:
- calcium-based phosphate binders (calcium acetate and calcium carbonate)
- lanthanum (Fosrenol)
- sevelamer hydrochloride (Renagel)
Hyperphosphatemia is often a complication of chronic kidney disease. One way to reduce your risk is by slowing kidney damage. Protect your kidneys by treating the cause of your kidney disease.
- High blood pressure can weaken the blood vessels that supply oxygen-rich blood to your kidneys. Taking high blood pressure medicines like angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers can lower your blood pressure and protect your kidneys.
- Extra fluid in your body can overwhelm your damaged kidneys. Taking a water pill (diuretic) can help restore the correct fluid balance in your body.
- Protein in your diet causes your body to produce more waste from protein metabolism, which your kidneys then have to filter out. Eating a lower-protein diet can help reduce these wastes and take some of the load off your kidneys.
High phosphate levels in your blood can increase your risk for serious medical problems and other complications. Treating hyperphosphatemia with dietary changes and medicines as soon as possible can prevent these complications. Getting treated can also slow bone problems linked to chronic kidney disease.