Testing Your Magnesium Levels


Magnesium Basics

Why test your magnesium?

As We Know from Pryor Pryor blog posts about magnesium oh, magnesium deficiency is extremely common officially impacting between 60 to 80% of people but most likely impacting over 90% of people given the outdated nature of statistics.

This makes testing your magnesium levels an important topic if you want to take a very calculated approach about managing and improving your body's magnesium supply. in this blog post we will cover the four different types of magnesium tests along with the pros and cons of each.  Let's start with the most common test which is used in standard medical practices in North America:


1. Serum blood test (most used, least reliable):

Unfortunately, it may not be easy to accurately determine the degree to which you are deficient in magnesium by using the standard method, which is a serum blood test. The results of this test reflect the amount of magnesium in our bodies' blood serum, which is only about 1% of the total amount of magnesium in our bodies. As such, this test fails to accurately identify cases of magnesium deficiency since the body's serum magnesium levels are tightly regulated to remain within the healthy range (1.5 - 2.4 mg/dl or 0.7 - 1 mmol/L).

This is important because the human body prioritizes magnesium in the serom over magnesium in other body parts, due to magnesium’s essential role as an electrolyte in your blood. If magnesium drops too low in your blood, it can result in death. SO the reality is That your organs and tissues and cells can constantly be being depleted of their magnesium in order to keep your blood levels stable and as such you can be heavily magnesium deficient but the serum blood test would show that your levels are healthy. This is why the serum magnesium blood test is not as reliable as others tests; because the blood serum does not paint an accurate picture of the rest of your body when it comes to magnesium levels.


“Serum and red blood cell magnesium concentrations have been shown to be poor predictors of intracellular magnesium concentration.”[6]

Dr. Ronald Elin - Department of Pathology and Laboratory Medicine - University of Louisville


“Normal serum and plasma magnesium concentrations have been found in individuals with low magnesium in [red blood cells] and tissues. Yet efforts to find an indicator of subclinical magnesium status have not yet yielded a cost-effective one that has been well validated.”[7]

Professor Judy Driskell - Department of Nutrition and Health Sciences - University of Nebraska


In the Journal of the American College of Nutrition Drs Dierck-Harmut and Dierck-Ekkehard Liebscher state that serum testing leads to 50% of magnesium deficiencies being untreated that.[8]

2. Exatest - Highest accuracy, lowest accessibility

The Exatest is the most accurate test for measuring magnesium levels in the body and it is far superior to the serum blood tests most commonly used. This test takes a sample of the sublingual epithelial cells in the lining of your mouth by using a scraper tool. So it does not measure your blood serum but rather it measures your body's cells where 99% of your magnesium should be. If you really want maximum accuracy this is the test to use however there are some things that you should know about it first.

Firstly, this test is not widely available; there is only one laboratory in the world that is able to process Exatest samples and provide results, located in Medford Oregon, USA. 

Furthermore, due to the expensive nature of the test (costing hundreds of dollars) it is usually not covered by healthcare insurance, making it an expensive method for some. 

Finally, extracting a sample from a person’s sublingual cells requires skill on behalf of the health professional in order to ensure accuracy - and even then there is still potential for mistakes, especially given that most health professionals have no experience with the Exatest..

Despite its accuracy, for most people the Exatest may not be the most practical option due to its cost and lack of availability. However, if you do decide that using the Exatest is right for you then it’s important to make sure that you find an experienced health professional who can take a sample correctly and accurately. Additionally, it’s also important to remember that this type of testing can be very expensive without medical insurance coverage; therefore you should make sure you are aware of all costs before committing to this method.


3. RBC test (highly accurate, more accessible):

The RBC test stands for the red blood cell test. This test measures the amount of magnesium in the red blood cells throughout your blood which are different than your blood's serum. your red blood cells actually much better reflect the magnesium levels in the rest of the cells that make up all of your different organs and tissues and bones and so on. This makes the Magnesium RBC test much more accurate than the serum blood test which is commonly used. 

While the RBC test is not as accurate as the Exatest, It is still highly reliable in its accuracy and it is also much more widely covered by health insurance companies than the Exatest.

Furthermore the Magnesium r b r b c test is not as expensive as the exit test. In fact it's much more affordable and it's also much more accessible. You can access this test for around the $100 range at websites such as  Request-a-test and Dynacare.

The Magnesium RBC test has the  balance of price, accessibility and accuracy for anyone who wants to properly measure their body's magnesium levels in the pursuit of accurately restoring their magnesium.

Is testing required?

Testing your magnesium is a great way to be absolutely sure of your degree of deficiency. Who knows you may even have a pleasant surprise and learn that you're one of the very few people who is not deficient in magnesium. However here's the great part about magnesium. It is extremely difficult to overdose on magnesium for multiple reasons. 

First of all because your body's systems are all heavily dependant on magnesium, this means your body's mechanism for regulating magnesium is extremely efficient. Even taking super high doses of concentrated magnesium supplements so far has only shown at worst to cause some loosening of the stools, diarrhea (or perhaps some cramping).  Having said that, this is extremely difficult to do with diet or transdermal supplements such as Epsom salts. This generally can only be achieved with a very high dose of a magnesium supplement taken orally and even then it is very difficult to achieve a level that can be considered toxic to humans. Remember, magnesium is needed nby your body more than any other element besides water and oxygen. In fact, your body needs magnesium in order to make use of the oxygen you breath, so overdosing on magnesium is extremely, extremely rare.

In the next post, we’ll talk about Magnesium in diet.

Posted By

Janelle Van Driesen

Janelle is one of our passionate writers that loves helping people understand health and nutrition.