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Blood Test: Magnesium

What Is a Blood Test?

By taking and testing a small sample of a person’s blood, doctors can check for many kinds of diseases and conditions. Blood tests help doctors check how the body’s organs are working and see if medical treatments are helpful.

What Is Magnesium?

Magnesium (pronounced: mag-NEEZ-ee-im) is a mineral that helps muscles, nerves, the immune system, and the heart work as they should. It also helps make protein and energy, and helps keep bones strong.

Why Are Magnesium Tests Done?

This test measures the amount of magnesium in the blood. Doctors may order a magnesium test if a person has signs of low magnesium levels, such as weakness, muscle cramps or twitching, or an unusual heartbeat. The test also can be done if someone has a medical condition that makes abnormal magnesium levels more likely, such as a kidney problem.

Are There Any Risks From Magnesium Tests?

A magnesium test is a safe procedure with minimal risks. Some people might feel faint or lightheaded from the test. A few teens have a strong fear of needles. If you're anxious, talk with the doctor before the test about ways to make the procedure easier.

A small bruise or mild soreness around the blood test site is common and can last for a few days. Get medical care if the discomfort gets worse or lasts longer.

What if I Have Questions?

If you have questions about the magnesium blood test, or what the test results mean, talk to your doctor.

Reviewed by: Larissa Hirsch, MD
Date Reviewed: Apr 10, 2023

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