Is Micronutrient Testing Accurate?

Oct 17 / Drs. Bryan & Julie Walsh

Have you ever wondered about the accuracy of micronutrient testing?

You know, the laboratory tests that evaluate a patient’s vitamin and mineral status.

They sound incredible, but are they too good to be true?

We investigated the accuracy of micronutrient testing and found some interesting information.

In this article, we're going to focus on what we found on one of the more well-studied and popular micronutrients in the Functional and Nutritional Medicine industry - magnesium.

But first, let’s cover some basics.

Micronutrients are critical for the optimal health of every single cell in the body. Many practitioners talk about the importance of carbohydrates, proteins, and fats, but fail to mention that, using carbohydrates, proteins, and fats in the body requires micronutrients.

In other words, without optimal levels of micronutrients, nothing works properly.

Our cells cannot make energy properly, we can’t detoxify or get rid of wastes properly, our brain won’t make neurotransmitters properly, hormones won’t work properly – micronutrients are the unsung hero in biochemistry, physiology, and overall wellness.

Unfortunately, there is no one way to test for all micronutrients at one time or in one tissue.

I know, bummer, right?

The truth is, some are better tested in the hair, some in blood, some in urine, some in cells, etc.

But, in terms of a single, comprehensive test, that accurately identifies a patient's micronutrient deficiencies - so that you know exactly what vitamins to give them - sorry, it does not exist.

To take a better look at the different ways of testing for micronutrient deficiencies, and how accurate they may be, let’s take a look at one of the most popular micronutrients in the Functional and Nutritional Medicine industry – magnesium.

Serum Magnesium – There are a few studies evaluating hypertensive patients taking diuretics (thiazides) which found that serum magnesium was normal, or even elevated, despite low levels of magnesium in mononuclear cells. This alone suggests the possibility of normal serum magnesium levels, despite deficient intracellular levels.
RBC Magnesium – This is one of the more popular ways to evaluate magnesium in the Functional and Nutritional Medicine industry, despite the fact that that there are significant issues with it as a reliable marker of magnesium status. For example, there aren't any long-term studies using RBC magnesium, too few randomized clinical studies, and not enough studies comparing RBC magnesium to something more reliable, such as the magnesium loading test or skeletal muscle magnesium. Not to mention that blood contains a mere 0.8% of the body's stores of magnesium, yet is somehow supposed to accurately reflect the remaining 99.2% of magnesium in the body.
Urinary Magnesium – In a study evaluating almost 100 people experiencing symptoms of chronic fatigue, almost half of them were determined to be magnesium deficient using a magnesium intravenous loading test. Despite this, the mean values of serum magnesium, red blood cell magnesium, and urinary magnesium showed no significant difference between people with or without magnesium deficiency.
Ionized Magnesium – Despite the fact that is it used far less often as a marker of magnesium status, in a study evaluating critically ill patients, ionized magnesium was considered to be an insensitive marker of functional magnesium deficiency when compared to the magnesium loading test.