Blood (Serum) Magnesium Level Test

What is the blood magnesium test?

This test measures the amount of magnesium in your blood. Magnesium is needed for your nervous, gastrointestinal, and cardiovascular systems to work normally. Your body gets magnesium from certain foods.

Why is this test done?

The magnesium level in your blood may be measured to check your:

• diet
• overall health
• kidney function
• endocrine (glandular) system.

How do I prepare for this test?

• You don't need to fast or limit your activity before the test.
• You may need to avoid taking certain medicines before the test because they might affect the test result. Make sure your healthcare provider knows about any medicines, herbs, or supplements that you are taking. Don't stop any of your regular medicines without first consulting with your healthcare provider.
• Talk to your provider if you have any questions.

How is the test done?

A small amount of blood is taken from your arm with a needle. The blood is collected in tubes and sent to a lab.

Having this test will take just a few minutes of your time. There is no risk of getting AIDS, hepatitis, or any other blood-borne disease from this test.

How will I get the test result?

Ask your healthcare provider when and how you will get the result of your test.

What does the test result mean?

The normal range for adults in most labs is 1.25 to 2.5 milliequivalents (mEq) per liter. The normal range may vary slightly from lab to lab. Normal ranges are usually shown next to your results in the lab report.

Your blood level of magnesium may be higher than normal if:

• You have kidney disease.
• You have a glandular disorder; for example, if your thyroid gland isn't making enough thyroid hormone.
• You have an illness or injury that causes muscle breakdown.

Your blood level of magnesium may be lower than normal if:

• You aren't getting the nutrients you need from your diet.
• You have frequent or long-lasting diarrhea.
• You drink too much alcohol.
• You have liver, pancreas, or kidney disease.
• You have too much calcium in your blood.
• You have severe burns.
• You have severe infections.
• You are taking certain medicines, such as digoxin, insulin, and diuretics (also called "water pills," used to treat high blood pressure).

What if my test result is not normal?

Test results are only one part of a larger picture that takes into account your medical history and current health. Sometimes a test needs to be repeated to check the first result. Talk to your healthcare provider about your result and ask questions.

If your test results are not normal, ask your healthcare provider:

• if you need additional tests
• what you can do to work toward a normal value
• when you need to be tested again.

If your magnesium level is low, you can take supplements to bring it back up.