Serum Phosphate Vs. Phosphorus

Phosphorus is a mineral found in a wide variety of foods. When you eat these foods, your body takes their phosphorus content and creates a related substance called phosphate. Most of this phosphate is held in your bones; however, a small percentage of it, called serum phosphate, circulates in your bloodstream.

Phosphorus-Containing Foods

Phosphorus is also commonly added to processed food as a thickening agent or taste enhancer, or to stop unwanted alterations in food color. Additives that contain phosphorus include monopotassium phosphate, phosphoric acid, pyrophosphate polyphosphate, disodium phosphate and calcium phosphate.

Serum Phosphate

Phosphate is formed in your body when phosphorus combines with oxygen. Only 1 percent of your body’s phosphate supply circulates in your bloodstream, according to a July 7, 2010 article in the Journal of the American Academy of Physician Assistants. Roughly 90 percent of this circulating phosphate floats free, while the remaining 10 percent is bound to proteins in the blood. Serum phosphate plays a vital role in helping the body properly regulate its electrical status, as well as its acid-base balance, or pH. Typically, blood levels of phosphate range anywhere from 3.0 to 4.5 mg/dL.

Low Phosphate Effects

If your serum phosphate levels fall below 2.5 mg/dL, you can develop a condition called hypophosphatemia, the "Merck Manual for Healthcare Professionals" explains 2. Potential causes of this condition include starvation, alcoholism, severe burns, use of diuretic medications and a health disorder called diabetic ketoacidosis. Most people with hypophosphatemia show no outward sign of their condition. However, potential consequences of the disorder include:

  • abnormal weakness in your muscles
  • seizures
  • heart failure
  • respiratory failure
  • coma
  • death

Treatment for hypophosphatemia commonly includes the use of oral or intravenous phosphate.

High Phosphate Effects

If your serum phosphate levels rise above 4.5 mg/dL, you can develop a condition called hyperphosphatemia. Common causes of this condition include low function in your parathyroid glands, chronic kidney failure and a disorder called acidosis. As with hypophosphatemia, people with hyperphosphatemia frequently have no noticeable symptoms. However, people with high phosphate levels commonly have low blood calcium levels, which can trigger symptoms that include calcium deposits in soft tissue and a form of involuntary muscle contraction called tetany.

Limiting Phosphorus

You can limit hyperphosphatemia’s effects by reducing your intake of high-phosphorus foods, the Mayo Clinic notes. Suitable low-phosphorus substitutes include:

  • refined grain products
  • unfortified rice milk
  • green beans
  • butter
  • cream cheese
  • cottage cheese
  • potatoes
  • rutabagas
  • frozen green peas
  • sherbet
  • poultry
  • pork
  • beef

However, because of the prevalence of phosphorus additives, you may need the help of a registered nutritionist to make an eating plan that excludes enough of the mineral from your diet. Consult your doctor for additional phosphorus and phosphate information.

The Wrap Up

However, people with high phosphate levels commonly have low blood calcium levels, which can trigger symptoms that include calcium deposits in soft tissue and a form of involuntary muscle contraction called tetany. When you eat these foods, your body takes their phosphorus content and creates a related substance called phosphate. You can limit hyperphosphatemia’s effects by reducing your intake of high-phosphorus foods, the Mayo Clinic notes.

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