Magnesium Test: About This Test

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What is it?

This test checks the level of magnesium in your blood. Magnesium is an important electrolyte. It's needed for proper muscle, nerve, and enzyme function. It also helps the body make and use energy.

Most of the magnesium in the body is found in the bones and inside the cells. Only a tiny amount of magnesium is normally found in the blood.

Why is this test done?

This test is used to:

  • Find a cause for nerve and muscle problems, such as muscle twitches, irritability, and muscle weakness.
  • Check how well your kidneys are working.
  • See if people with heart problems need extra magnesium. (Low magnesium levels can increase the chances of life-threatening heart rhythm problems.)
  • Measure levels when magnesium is being given for medical treatment.

How can you prepare for the test?

  • Don't take medicines containing magnesium for at least 3 days before this test. This includes:
    • Antacids that contain magnesium.
    • Laxatives (such as milk of magnesia or Epsom salts).
    • Magnesium supplements.
    • Some diuretics.

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.

How long does the test take?

  • The 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?

Go to http://www.healthwise.net/ed

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Current as of: February 19, 2016