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Magnesium Test for Deficiency. Magnesium Test Results

Magnesium Test For Deficiency: What You Need To Know in (2023)?

Magnesium Test for Deficiency. Magnesium Test Results for Serum/ Blood Test, RBC Magnesium Test, Urine Magnesium Test.

Magnesium is an essential mineral for the human body, and it plays a crucial role in maintaining healthy bones, muscles, and nerves. Magnesium is also involved in vital biochemical reactions in the body, like energy production, protein, and DNA synthesis. In this article, we will discuss the different methods of testing Magnesium in the blood and urine, the normal range of Magnesium in healthy human beings, and how to interpret Magnesium test results.

Though Magnesium is widely abundant in our diet, still around 80% of the American population found deficient in this essential mineral. To measure the level of Magnesium in our body and to ascertain the exact cause of Mg deficiency there are various test prescribed by “healthcare workers”. The most widely followed Mg test method by healthcare providers around the world to determine Magnesium deficiency in humans is discussed below.

The Serum (Blood) MagnesiumTest for Deficiency 

The Serum Magnesium ion Test Method ascertains the amount of Mg in the blood’s liquid part i.e. (the serum). Considered the most accurate method for determining Magnesium levels in the body.  This test directly measures the amount of Magnesium available for utilization by the body’s cells. A blood (serum) evaluation can provide information on the total amount of Magnesium in the blood, which includes both bound and unbound Mg. Bound Magnesium is the Mg that is attached to proteins, while unbound Mg is the Magnesium that is free in the blood in the form of Mg ions.

Blood Mg Test Procedure

  1. Ensure that the patient has fasted for 8 to 12 hours before the test. The patients should inform the health care provider about taking any Magnesium supplements or any other drugs. As various drugs hamper the Magnesium ion test results. The patient must have information about the test procedure and potential risks.  (though in this test there are no significant risks apart from a small sting of a needle).
  2. During a Serum Mg Assay, a healthcare professional will draw a sample of blood from the vein of your arm using a sterile needle. The blood sample is then sent for an assay test.
  3. The collected blood sample is transferred to a labeled tube and allowed to clot for at least 30 minutes.
  4. Then Centrifuge the tube at 3000 rpm for 10 minutes in a centrifuge machine. This step separates the serum from the blood clot.
  5. To determine Magnesium levels, the process involves using a Magnesium assay kit. The Kit includes specific reagents capable of reacting with Magnesium to produce a colored end product. A colorful end product is then measured using a spectrophotometer. Several Magnesium-specific reagents, such as Magnesium Green and Xylenol Orange, are utilized in these Magnesium assay kits..  These reagents are fluorescent dye that binds specifically to Magnesium ions to produce a color fluorescence. The fluorescence intensity is directly proportional to the Magnesium concentration, measured with the help of a fluorometer or spectrophotometer.

Results Interpretation for Blood Magnesium Test

Compare the Magnesium level in the patient’s serum with the reference range of 1.6 to 2.6 mg/dL. A level outside of the reference range may indicate a Magnesium deficiency or excess. However, it’s important to note that blood Magnesium levels can fluctuate throughout the day and may not accurately reflect overall Mg status.

RBC(Red Blood Cell) Magnesium test

The RBC (Red Blood Cell) Magnesium test measures the amount of Mg in the red blood cells. The test is used to evaluate Magnesium deficiency or excess in the body.

The principle behind the RBC Mg ion test is based on the fact that Magnesium ions are incorporated into the red blood cells during their formation in the bone marrow. Therefore, the concentration of Magnesium in the RBC reflects the body’s Magnesium status over a longer period of time. Meanwhile, the serum Mg test measures the concentration of Mg in the blood plasma at a single point in time.

RBCs are analyzed for Magnesium because they contain high concentrations of Mg and have a lifespan of approximately 120 days, making them an excellent indicator of Magnesium levels over an extended period. Magnesium primarily binds to the protein inside RBCs, making them a reliable source for assessing Magnesium status compared to other cells or blood components. Additionally, separating RBCs from whole blood is simple, making them a convenient and dependable sample for measuring Magnesium levels in the body.

RBC Magnesium Test Procedures 

  1. Sample collection: A blood sample is collected from the patient using a needle and syringe.
  2. Red blood cell Lysis: A centrifuge is used to separate the red blood cells from the plasma, and then they are lysed (i.e., broken down) to release their Magnesium content.
  3. Magnesium extraction: The chemical solution, such as hydrochloric acid, extracts the Magnesium ions from the lysed red blood cells..
  4. Colorimetric reaction: The extracted Magnesium ions are mixed with a colorimetric reagent such as calmagite, which reacts with Mg ions to produce a colored complex. The intensity of the color is proportional to the amount of Mg ions present in the sample.
  5. Absorbance measurement: A spectrophotometer measures the absorbance of light by the colored complex to determine the intensity of the color. The absorbance values are then compared to calibrated Magnesium standards to determine the concentration of Mg in the sample.

RBC Magnesium Test Results Interpretation

Levels of RBC Mg Test may be a better indicator of overall Mg status than blood Magnesium levels. The reference range for RBC Magnesium levels is typically between 4.2 and 6.8 milligrams per deciliter (mg/dL). Low levels may indicate a Magnesium deficiency, while high levels may indicate excess Magnesium intake.

Urine Magnesium Test

The Urine Magnesium Test measures the amount of Magnesium in a person’s urine, serving as a diagnostic test. This test is useful in diagnosing Magnesium deficiency or excess, as well as kidney-related issues that affect the body’s ability to eliminate Magnesium.

 The Steps and procedures for Urine Magnesium test

  1. Pre-test Preparation: Before the test, the person will need to abstain from taking any medications or supplements that may affect Magnesium levels, such as diuretics, antacids, or laxatives. The patient will also need to collect a 24-hour urine sample in a container provided by the laboratory. It is important to follow the specific instructions given by the laboratory for the collection of the urine sample.
  2. Urine Collection: The urine sample must be collected over a 24-hour period. The patient should discard the first-morning urine sample and start the collection from the second urine. The patient should collect all urine during the next 24 hours, including the first voided urine sample the next morning. The urine samples should be kept in a cool place, such as a refrigerator or cooler, during the collection period to prevent degradation of the Magnesium.
  3. Laboratory Testing: The urine sample is then sent to a laboratory for testing. The laboratory will measure the amount of Magnesium in the urine by using various chemical reagents that react with Magnesium ions in the urine. The test may be performed using a colorimetric method, which measures the intensity of color produced when Magnesium ions react with a specific reagent. The laboratory may also use other methods, such as atomic absorption spectroscopy, to measure Magnesium levels in the urine.

Urine Magnesium Test Results Interpretation

The Laboratory will provide the test results in milligrams (mg) of Magnesium per 24 hours. Normal ranges for urine Mg levels vary based on age and sex. Interpreting Magnesium ion test results requires an understanding of the normal range of Magnesium in healthy humans and the method used to measure Magnesium levels. As previously mentioned, the normal range of Magnesium in the blood is between 1.7 to 2.3 mg/dL or 0.7 to 0.95 mmol/L, while the normal range of Magnesium in the urine is between 80 to 260 mg/24h or 0.52 to 1.7 mmol/24h. Values outside this range may indicate a Magnesium deficiency or excess.

Magnesium Loading Test

A Magnesium Loading test is a medical test used to evaluate the body’s Magnesium levels and to diagnose Magnesium deficiency or excess. It involves administering a high dose of Magnesium through different Magnesium Supplements like Magnesium Glycinate, Magnesium Citrate, Magnesium Threonate, etc, and then measuring the amount of Magnesium excreted in the urine over a specified period of time.

The Mg loading test is a useful tool for diagnosing Magnesium deficiency in patients with chronic conditions such as kidney disease, gastrointestinal disorders, or alcoholism, as well as in patients with unexplained symptoms such as muscle weakness or heart palpitations. However, it is a time-consuming test and may not be necessary for all patients with suspected Magnesium abnormalities.

Steps and Procedures Involved in a Magnesium Loading Test

  1. Preparation: The patient is instructed to follow a specific diet and to avoid Magnesium-containing foods, supplements, and medications for a certain period of time before the test.
  2. Baseline Mg measurement: A blood sample is taken from the patient to measure their baseline Mg levels before the test.
  3. Magnesium loading: The patient is given a high dose of Magnesium, usually in the form of Mg sulfate or Magnesium citrate, either orally or intravenously.
  4. Urine collection: The patient collects all their urine for a specified period of time, typically 24 hours, in a container provided by the healthcare provider.
  5. Urine Magnesium measurement: The amount of Magnesium in the collected urine is measured using a urine Mg test.

Magnesium Loading Test Results Interpretation

Interpretation of results: The amount of Magnesium excreted in the urine is compared to the amount of Magnesium administered to the patient. If the patient passes a large amount of Magnesium in their urine, it indicates that their body has an excess of Magnesium. If they excrete a low amount of Mg, it indicates a deficiency.

Summary Of Magnesium Deficiency Test:

Overall, the RBC Magnesium deficiency test is considered to be the most accurate indicator of Magnesium status. The blood Magnesium test may not provide a complete picture of Magnesium levels due to fluctuations throughout the day, while the urine Magnesium test is more useful for detecting excess Mg intake rather than deficiency and finding kidney disorder. The Magnesium loading test can help identify the body’s ability to absorb and excrete Mg but is not routinely used in clinical practice.

In summary, the choice of which Mg ion test to use depends on the clinical context and the specific question being asked. Each test has its own advantages and limitations, and a combination of tests may be necessary to obtain a comprehensive evaluation of Magnesium status.

Here is a table with the normal ranges for Serum/ Blood Mg Test, RBC Magnesium Test, and Urine Magnesium ion Tests in different age groups:

Comparison between Blood Magnesium Test, RBC Magnesium, and Urine Magnesium Test Result range
Magnesium Test Result Range

Please note that reference ranges may vary depending on the laboratory and method used for the test and that the values provided here are meant as a general guide only. It’s important to interpret test results in the context of an individual’s overall health and medical history. These are general ranges and may not apply to every individual case. It’s always best to consult with a healthcare professional for the interpretation of test results.

FAQ (Frequently Asked Questions)

Magnesium test normal range?

Adult 1.6 – 2.6 mg/dL for blood Magnesium test to learn more please refer the table above.

How do I know if I am low on Magnesium?

There are various signs and symptoms to look out for Magnesium deficiency like Muscle cramps, fatigue & weakness, abnormal heart rhythms, mood swings, numbness etc. you can learn more about sign & symptoms of Magnesium deficiency in this article.

How can I fix my Magnesium deficiency fast?

By taking Magnesium rich foods & supplements to learn more you can check this article.

How to test for Magnesium deficiency at home?

While it is possible to test for Magnesium levels at home using self-testing kits, it is generally not recommended. Home testing kits for Magnesium are not as accurate or reliable as those used in a medical laboratory, and the results may not be interpreted correctly without proper training and expertise.
There are some self-testing kits available in the market for those who still want to proceed with at-home testing. But it is important to note that these self-testing kits may not be covered by insurance, and they may not provide accurate or comprehensive information about a person’s Magnesium status. In addition, if the results are abnormal, it is important to consult with a healthcare provider to determine the underlying cause and appropriate treatment.

Which is the most widely followed Magnesium test method by healthcare providers?

The most reliable and widely followed Magnesium test method by healthcare providers around the world to determine Magnesium deficiency in humans is the serum Magnesium test and RBC Magnesium test.

What are the methods to measure Bone Magnesium levels?

Bone biopsy: A small piece of bone is removed and analyzed in a laboratory to determine its Magnesium content. This method is invasive and not commonly used.

X-ray fluorescence (XRF): This method uses X-rays to measure the amount of Magnesium in bone. It’s non-invasive, but may not be as accurate as other methods.

Dual-energy X-ray absorptiometry (DEXA):
This is a common test used to measure bone density, but it can also provide information on bone Magnesium levels. DEXA uses low-dose X-rays to produce images of the spine, hip, or other bones. The images can be used to calculate bone density and Magnesium content.
Magnetic resonance spectroscopy (MRS): This method uses magnetic fields and radio waves to produce images of the body’s tissues. MRS can be used to measure the concentration of Magnesium in bone and other tissues.


You can take help from the following sites for extra learning, Author has referred to various Science and Research Journal and University studies to enumerate the article above.


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