Phosphate in Urine

A phosphate in urine test measures the amount of phosphate in a urine (pee) sample that you collect over a 24-hour period. Phosphate contains the mineral phosphorus. So, a phosphate test is sometimes called a phosphorus test.

Phosphate is an electrolyte. Electrolytes are electrically charged minerals. They help control the amount of fluid and the balance of acids and bases (pH balance) in your body.

Your body also needs phosphates for many other important processes, such as: Building strong bones and teeth. Most of the phosphate in your body is found in your bones where it is combined with the mineral calcium.; Making energy.; Helping your nerves and muscles work properly.; The phosphorus in phosphate comes from the foods you eat, including nuts and seeds, dairy products, dried beans, meats, poultry, and eggs. Your body tightly controls the amount of phosphate in your blood mainly through your: Kidneys.

They filter extra phosphate from your blood and get rid of it through urine (pee). If your phosphate level is low, your kidneys limit the amount lost through urine.; Intestines. They control how much phosphorus you absorb from the foods you eat.; The amount of phosphate in your body is also linked to your levels of: Calcium.

When calcium levels increase, phosphate levels decrease. And when calcium levels decrease, phosphate levels increase.; Vitamin D. It helps your body use phosphate.; Parathyroid hormone (PTH).

This hormone is made by parathyroid glands in your neck. It helps balance phosphate and calcium levels.; Abnormal phosphate levels may be a sign of problems with the systems in your body that control phosphate levels. These include various kidney conditions and disorders of the parathyroid glands.

Why this test is done

You may need a phosphate in urine test if you have:

• Had an abnormal result on a phosphate in blood test.
• Had a kidney stone.
• Had an abnormal result on a blood or urine calcium test. Calcium and phosphate work together, abnormal calcium levels may mean you have abnormal phosphate levels, too.
• Symptoms of a kidney problem.
• Problems with your electrolyte balance, which affects your acid/base (pH) level.

How to prepare

You don't need any special preparations for a phosphate in urine test. Be sure to carefully follow all the instructions for providing a 24-hour urine sample.

Sample type

Urine

Other names for this test

phosphorous test, PO4, inorganic phosphate, PO4 urine concentration