What Is a Serum Magnesium Test?
important to the functioning of your body. According to the National
Institutes of Health (NIH), this mineral plays a role in more than 300 of
your body’s biochemical reactions. For example, it helps regulate blood
pressure and your heartbeat. It also helps maintain bone strength. Having too
little magnesium in your body can negatively affect all of these functions.
Many common foods contain magnesium. Rich magnesium sources
- green vegetables, such as spinach
Your tap water may also contain magnesium.
It’s possible to have too much magnesium. In rare cases, magnesium
overdoses can lead to cardiac arrest and death. It’s rare to overdose on
magnesium through food alone. Instead, magnesium overdose may be due to taking too
many magnesium supplements.
You might need to take supplements if you have certain conditions
such as diabetes, alcoholism, or an issue absorbing nutrients. You may also
take them if you have low potassium and calcium levels in your blood.
If your doctor suspects that your magnesium level is too low or
too high, they may order a serum
This test involves a basic blood draw. Your doctor will collect
some of your blood into a vial or tube and send it to a lab for testing.
Why Do I Need a Serum Magnesium Test?
Your doctor may order a serum magnesium test if they suspect your
magnesium level is too low or too high. Either extreme can lead to health
problems. This test may also be ordered if you have chronic low potassium and
calcium levels. Magnesium plays a role in regulating the calcium and potassium
levels in your body. Your doctor may check your magnesium if these levels are
This test may also be necessary if your doctor thinks you might
have a malabsorption or malnutrition problem. You may have this test regularly
if you have diabetes or kidney problems. This helps your doctor stay on top of
Symptoms of magnesium deficiency initially include:
- appetite loss
As the deficiency progresses, you may experience:
- numbness and tingling
- muscle cramps
- personality changes
- abnormal heart rhythms
The signs and symptoms of an overdose include:
- slowed heart rate
- upset stomach
- very low blood pressure
On rare occasions, cardiac arrest or death from a magnesium
overdose can occur.
Your doctor might order this test if your symptoms suggest either
a magnesium deficiency or an overdose.
provides a list of foods high in magnesium. Wheat bran, dry roasted almonds,
and cooked frozen spinach are at the top of the list. Each one of these foods
provides only about 20 percent of your daily value of magnesium per serving.
It would be hard to eat too much magnesium. Overdoses usually
happen when someone consumes too much supplemental magnesium. You may take
supplements if you have diabetes or alcoholism. Your doctor may also instruct
you to take them if you have Crohn’s disease.
What Are the Risks Associated with the Serum
You can expect to feel some minor pain during a blood draw. You
might also continue to bleed slightly for a few minutes after the procedure.
You may get a bruise at the needle insertion site.
Serious risks are rare and include fainting, infection, and
What Do the Results Mean?
The normal range for serum magnesium is 1.7 to 2.3 milligrams per
The exact standards for normal results may vary depending on your:
The standards also depend on the lab performing the test.
Discuss your results with your doctor to get more precise
High levels of magnesium usually are not a result of consuming
too much as part of your diet. Instead, they often result from having too many
supplements. In other cases, high levels are due to a problem with excreting
Specific conditions that can lead to high magnesium levels
- Addison’s disease, which is a disorder of the
- thyroid issues including hypothyroidism or
- diabetic acidosis
- kidney failure
- oliguria, or low urine production
Low levels, on the other hand, can indicate that you don’t eat
enough of this mineral. Sometimes, low levels mean that your body isn’t keeping
enough of the magnesium that you eat. This can happen in cases of:
- chronic diarrhea
- hemodialysis, which is a mechanical way to
filter waste products from the blood when the kidneys don’t function properly
- gastrointestinal disorders, such as Crohn’s
disease, which is an inflammation of the bowel
- ongoing use of diuretics
There are quite a few other possible causes of low magnesium.
- heavy periods
- issues with specific conditions, including
hepatic cirrhosis, hyperaldosteronism, and hypoparathyroidism
- severe burns
- excessive sweating
- toxemia of pregnancy
- ulcerative colitis, which is an inflammation of
the bowel that affects the large intestine
- uncontrolled diabetes
Low levels can also occur in alcoholism and during the course of
a condition caused by alcohol withdrawal called “delirium tremens,” which involves
trembling, agitation, and hallucinations.
High and low magnesium levels have a wide variety of causes. You
should work with your doctor to find out the cause of your symptoms.