Magnesium Blood Test Test
A magnesium blood test measures the amount of magnesium in your blood. Magnesium is a mineral that helps your muscles, nerves, and heart work properly, controls blood pressure and blood sugar, builds strong bones, and supports your immune system.
What this test measures
This test measures the amount of magnesium in a sample of your blood. Magnesium is an electrolyte that helps control fluid and acid-base balance in your body.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
Higher than normal magnesium levels may mean you are getting too much magnesium from supplements, laxatives, antacids, or certain medicines. It can also mean your body has trouble getting rid of magnesium, most commonly due to kidney failure. Other causes include dehydration, hypothyroidism, Addison disease, and overactive parathyroid glands.
Lower-than-normal results
Low magnesium levels may mean you are not getting enough magnesium in your diet, your body cannot absorb it properly (due to digestive disorders or certain medicines), or your body is losing too much magnesium (due to kidney problems, long-term diarrhea, or diabetes). Other causes include underactive parathyroid glands and pregnancy.
Frequently asked questions
What is a magnesium blood test?
It measures the amount of magnesium in your blood. Magnesium is a mineral that helps your muscles, nerves, and heart work properly.
Why might I need this test?
Your provider may order it if they think your magnesium levels are not normal. It can help diagnose conditions like magnesium deficiency or excess.
What does a low magnesium level mean?
It may mean you are not getting enough magnesium, your body is not absorbing it, or you are losing too much. Causes include poor diet, digestive disorders, kidney problems, or diabetes.
What does a high magnesium level mean?
It may mean you are getting too much magnesium from supplements or medicines, or your body cannot get rid of it. The most common cause is kidney failure.
How does my body control magnesium levels?
Your kidneys filter extra magnesium and remove it through urine. Your intestines control how much magnesium you absorb from food.
Related lab tests
Sources
- MedlinePlus: Magnesium Blood Test — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.