Blood test

High magnesium level in the blood

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

What is high magnesium in the blood called?

  • Hypermagnesemia

What is the normal level of magnesium in the blood?

If you need to know which are the magnesium reference ranges or you require more information about the role of magnesium in the blood, you can visit normal magnesium level in the blood

What does a high magnesium level in the blood mean?

In patients with an adequate renal function, any excess of magnesium in the blood is excreted into the urine by the kidneys. Renal excretion is the major route of magnesium elimination from the body. High magnesium levels in the blood can be expected under conditions of renal failure.

Hypermagnesemia or high magnesium blood level is a sign of uremia, kidney failure, glomerulonephritis, Addison's disease or it can be seen in people under treatment with magnesium-containing antacids.

Magnesium blood values are usually given in mg/dl but sometimes you can see those values in mEq/L or mmol/l following the International System of Units (SI). In case your values are in another unit you can convert them using this tool:

  • Mild hypermagnesemia (2.6 - 3 mg/dl in adults):

    Your magnesium level is a bit high but it is not a matter for concern.

    It may be due to a mild to moderate dehydration or because you are taking medication for another disease.

    Contact your doctor if you are taking medication and try to do a new blood test in a few months to know if values return to normal level.

  • Moderate hypermagnesemia (3 - 5 mg/dl in adults):

    Magnesium level in the blood is moderately high but not alarming. Probably you are asynthomatyc.

    It may be due to a kidney failure so it is advisable to perform some screening test to diagnose your kidneys functionality. A study of your thyroid gland can be also interesting to exclude hypothyroidism. Addison’s disease may also be a possibility.

    A visit to your doctor is recommended. Tell him any medication you are taking because there are some drugs that contain magnesium.

  • Marked hypermagnesemia (5 - 8 mg/dl in adults):

    Your magnesium level in the blood is so high that you are probably suffering from nauseas or headache.

    If your doctor thinks it appropriate, you may require hospitalization because marked hypermagnesemia is dangerous for the body.

  • Severe hypermagnesemia (> 8 mg/dl in adults):

    Your magnesium level is so high that you must find urgent medical attention.

    Severe hypermagnesemia causes symptoms like drowsiness and bradycardia (slower than normal heart rate). If the magnesium blood level is above 12 mg/dl you can experience paralysis and heart failure.

Which factors can raise magnesium level in the blood?

There are some health circumstances or drugs than can raise your magnesium level in the blood:

  • Dehydration (due to excessive sweating, vomiting or diarrhea)
  • Drugs
    • Antacids
    • Aspirin
    • Diuretics
      • Triamterene
    • Progesterone
    • Psychotropic drugs
      • Lithium
    • Magnesium salts

Which diseases can raise your magnesium level in the blood?

There are many medical conditions why the magnesium level in the blood can be higher than normal:

  • Hyperparathyroidism
  • Nephrolithiasis

What can I do to lower magnesium level in the blood?

If your magnesium level in the blood is slightly high, you may consider the following tips:

  • Reduce your magnesium intake. There is plenty of magnesium in:
    • Green leafy vegetables such as spinach and kale
    • Chocolate
    • Nuts: Almonds, peanuts and walnuts
    • Fruits: Avocados, bananas
  • Avoid or reduce medication containing magnesium. Before doing this you must visit your doctor to follow his recommendation. He may give you alternatives drugs.

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

You can visit our pages about:

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

The following values are considered to be above the normal range:

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.

Mild hypermagnesemia
2.7 mg/dl2.8 mg/dl2.9 mg/dl3 mg/dl    
Moderate hypermagnesemia
3.1 mg/dl3.2 mg/dl3.3 mg/dl3.4 mg/dl3.5 mg/dl3.6 mg/dl3.7 mg/dl3.8 mg/dl
3.9 mg/dl4 mg/dl4.1 mg/dl4.2 mg/dl4.3 mg/dl4.4 mg/dl4.5 mg/dl4.6 mg/dl
4.7 mg/dl4.8 mg/dl4.9 mg/dl5 mg/dl    
Marked hypermagnesemia
5.1 mg/dl5.2 mg/dl5.3 mg/dl5.4 mg/dl5.5 mg/dl5.6 mg/dl5.7 mg/dl5.8 mg/dl
5.9 mg/dl6 mg/dl6.1 mg/dl6.2 mg/dl6.3 mg/dl6.4 mg/dl6.5 mg/dl6.6 mg/dl
6.7 mg/dl6.8 mg/dl6.9 mg/dl7 mg/dl7.1 mg/dl7.2 mg/dl7.3 mg/dl7.4 mg/dl
7.5 mg/dl7.6 mg/dl7.7 mg/dl7.8 mg/dl7.9 mg/dl8 mg/dl  
Severe hypermagnesemia
8.1 mg/dl8.2 mg/dl8.3 mg/dl8.4 mg/dl8.5 mg/dl8.6 mg/dl8.7 mg/dl8.8 mg/dl
8.9 mg/dl9 mg/dl9.1 mg/dl9.2 mg/dl9.3 mg/dl9.4 mg/dl9.5 mg/dl9.6 mg/dl
9.7 mg/dl9.8 mg/dl9.9 mg/dl10 mg/dl10.1 mg/dl10.2 mg/dl10.3 mg/dl10.4 mg/dl
10.5 mg/dl10.6 mg/dl10.7 mg/dl10.8 mg/dl10.9 mg/dl11 mg/dl11.1 mg/dl11.2 mg/dl
11.3 mg/dl11.4 mg/dl11.5 mg/dl11.6 mg/dl11.7 mg/dl11.8 mg/dl11.9 mg/dl12 mg/dl
12.1 mg/dl12.2 mg/dl12.3 mg/dl12.4 mg/dl12.5 mg/dl12.6 mg/dl12.7 mg/dl12.8 mg/dl
12.9 mg/dl13 mg/dl13.1 mg/dl13.2 mg/dl13.3 mg/dl13.4 mg/dl13.5 mg/dl13.6 mg/dl
13.7 mg/dl13.8 mg/dl13.9 mg/dl14 mg/dl14.1 mg/dl14.2 mg/dl14.3 mg/dl14.4 mg/dl
14.5 mg/dl14.6 mg/dl14.7 mg/dl14.8 mg/dl14.9 mg/dl15 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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