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Normal magnesium level in the blood

Blood test
Normal magnesium level in the blood
Last update: 24/03/2020

What is the normal level of magnesium in the blood?

Magnesium blood levels are usually expressed in mg/dl. Normal ranges are:

Adults: 1.6 to 2.6 mg/dl
Children: 1.7 to 2.2 mg/dl

Sometimes the values are given in mEq/L. In this case normal ranges are:

Adults: 1.3-2.1 mEq/L
Children: 1.4-1.8 mEq/L

In the International System of Units (SI), magnesium in the blood is measured in mmol/L. The valence of magnesium is +2 (1 mEq= 1 mmol / valence) so normal ranges are:

Adults: 0.65-1.05 mmol/L
Children: 0.72.2-0.9 mmol/L

Why normal levels can differ across different labs?

Each laboratory must establish its own normal ranges for magnesium in the blood. These ranges depend on the makeup of the local population, the technologies used and the accuracy of the measurement. There may be also slight differences in the normal levels according to age, gender, race or ethnic origin, geographic region, diet, type of sample and other relevant status.

Your doctor will study the results along with your medical record, screenings, physical condition, symptoms and any other relevant information about your situation.

What is the role of magnesium?

Magnesium is an electrolyte essential for neuromuscular function and intermediary metabolism. Magnesium has a strong relationship with the immune system.

Magnesium is an activator of different enzymes and participates in many metabolic processes such as the biological activity of ATP (adenosine triphosphate). Magnesium is necessary for the maintenance of the electrical potential of nervous tissues and cell membranes.

About 60% of the total magnesium is stored in the bones and 20% in the muscles. Magnesium can be also found in teeth, heart, nerves or arteries.

Less than 1% of total magnesium is in the blood. It can be found free or bound to proteins or anions. Magnesium, along with calcium, is essential for an adequate neuromuscular and cardiac activity.

Blood magnesium levels can remain stable even with a 20% decrease in total magnesium in the body.

Magnesium enters the body through the diet and it is excreted in the urine and stools.

What is a magnesium blood test used for?

A magnesium blood test is ordered to know:

  • If a person does not absorb enough magnesium from the diet.
  • If the kidneys are working properly.
  • If muscle and cardiac activity is correct.

The magnesium blood test is performed along with calcium, phosphorus, potassium and parathyroid hormone test. A person with low levels of magnesium may also have calcium and potassium deficiency.

Most cases of magnesium high levels in the blood (hypermagnesemia) occur in people who have kidney failure or who are taking magnesium-containing antacids.

When the magnesium level in the blood is low (hypomagnesemia) can be due to:

  • The body's inability to absorb the magnesium that is taken in through diet.
  • By renal or gastrointestinal losses.

The main consequence related to hypomagnesemia is suffering from arrhythmias.

Where can I find more information about magnesium in the blood?

You can visit our pages about:

Which values are considered a normal magnesium level in the blood?

The following values are considered to be normal values:

IMPORTANT: These levels are expressed in mg/dl. They are an example for a healthy man of about 45 years of age with no known disease, not taking any medication and with an appropriate intake of magnesium in the diet. The ranges can be different depending on the laboratory or on your personal circumstances.

1.6 mg/dl1.7 mg/dl1.8 mg/dl1.9 mg/dl2 mg/dl2.1 mg/dl2.2 mg/dl2.3 mg/dl
2.4 mg/dl2.5 mg/dl2.6 mg/dl     
Medically reviewed by Javier Muga Bustamante Ph.D. on 24/03/2020


  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 506.
  • Tietz. Fundamentals of Clinical Chemistry. Carl A. Burtis, Edward R. Ashwood, David E. Bruns, Barbara G. Sawyer. WB Saunders Company, 2008. Pag 719. ISBN: 978-0-7216-3865-2.
  • Common Terminology Criteria for Adverse Events (CTCAE). Version 5.0.Published: November 27, 2017. U.S. Department of health and human Services. Available on:

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