Magnesium Test: About Your Child's Test

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What is it?

This is a blood test that checks the level of magnesium in your child's blood. Magnesium is an important electrolyte. It's needed so that muscles, nerves, and enzymes work as they should. 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 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, muscle weakness, and irritability.
  • Check how well your child's kidneys are working.
  • Measure levels when magnesium is being given for treatment.

How do you prepare for the test?

Make sure to tell the doctor if your child takes:

  • Antacids that contain magnesium.
  • Laxatives (such as milk of magnesia or Epsom salts).
  • Magnesium supplements.

Your child may have to stop taking them for a time before the test.

How is the test done?

A health professional uses a needle to take a blood sample, usually from the arm.

How long does the test take?

The test will take a few minutes.

Follow-up care is a key part of your child's treatment and safety. Be sure to make and go to all appointments, and call your doctor if your child is having problems. Ask your doctor when you can expect to have your child's test results.

Where can you learn more?

Go to https://www.healthwise.net/patientEd

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The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.