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Phosphate in Blood: About This Test

What is it?

A phosphate test measures the amount of phosphate in your blood. Your body needs this mineral to build and repair bones and teeth, help nerves function, and make muscles contract.

The kidneys help control the amount of phosphate in your blood. A high level of phosphate is usually caused by a kidney problem.

Why is this test done?

A test to measure phosphate in blood may be done to:

  • Check phosphate levels if you have kidney disease or bone disease.
  • Help find problems with certain glands, such as the parathyroid glands.

How can you prepare for the test?

  • In general, you don't need to prepare before having this test. Your doctor may give you some specific instructions.

What happens during the test?

  • A health professional takes a sample of your blood.

What else should you know about the test?

  • Your results will include an explanation of what a "normal" result is. This is called a "reference range." It is just a guide. Your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed may still be normal for you.
  • The amount of phosphate in the blood affects the level of calcium in the blood, so phosphate and calcium levels are usually measured at the same time.

How long does the test take?

This test will take a few minutes.

What happens after the test?

  • You will probably be able to go home right away.
  • You can go back to your usual activities right away.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse call line if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.

Where can you learn more?

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