Blood test

Low magnesium level in the blood

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

What is high magnesium in the blood called?

  • Hypomagnesemia

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 low magnesium level in the blood mean?

Low magnesium level in the blood can be due to a variety of reasons. It is important to know the cause to apply an effective treatment.

Magnesium is supplied in the food we eat and it may be low in case of malabsorption.

Deficiency of magnesium is a frequent complication of inflammatory bowel disease (ulcerative colitis or Crohn's disease).

An excessive urinary excretion of magnesium, when there is a renal disease (like glomerulonephritis) or a problem associated with the thyroid gland, can lead to hypomagnesemia.

Magnesium deficiency is also related to pre-eclampsia in pregnancy.

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 hypomagnesemia (1.2 - 1.6 mg/dl in adults):

    Magnesium level in the blood is a bit low but it is not a cause for concern. It is advisable to eat more food high in magnesium and to avoid alcohol. If you are taking any medication talk to your doctor because it may have influence.

    If you follow these recommendations, your magnesium level in the blood could be optimal in the following test.

  • Moderate hypomagnesemia (0.9 - 1.2 mg/dl in adults):

    Weakness, dizziness or tremor is usually present with moderate hypomagnesemia.

    It is recommended a visit your doctor and if he considers it appropriate he can prescribe you magnesium oral supplements.

  • Marked hypomagnesemia (0.7 - 0.9 mg/dl in adults):

    Marked hypomagnesemia is a matter of concern and the possibility of suffer seizures or muscle spasms is present.

    Low magnesium values are presented usually alongside with low calcium and potassium levels in the blood. This combination exacerbates the problem.

    You must visit your doctor as soon as possible because it is essential to follow the appropriate treatment to recover a correct magnesium level in the blood.

  • Severe hypomagnesemia (< 0.7 mg/dl in adults):

    Magnesium levels are so low that you need to look for urgent medical attention. You may experience seizures, muscle spasms or arrhythmias.

    Severe hypomagnesemia not treated can lead to brachial artery occlusion (the major blood vessel of the upper arm).

    In addition, low magnesium blood level is often followed by hypocalcemia and hypopotassemia with an ever-increasing number of related problems.

    Parenteral magnesium replacement under medical supervision is the recommended practice for patients with severe hypomagnesemia. Magnesium is given by IV (intravenous) infusion of magnesium sulphate.

Which factors can reduce magnesium level in the blood?

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

  • Alcohol
  • Chronic diarrhea
  • Pregnancy
  • Malnutrition
  • Burns
  • Drugs
    • Antacids
      • Omeprazole
    • Antiarrhythmic agents
      • Digoxin
    • Antiasthmatic drugs
      • Albuterol
    • Antibiotics
      • Aminoglycoside
      • Amphotericin B
      • Carbenicillin
      • Gentamicin
      • Pentamidine
      • Ticarcillin
    • Antineoplastics
      • Cetuximab
      • Ciclosporin
      • Cisplatin
    • Citrates
    • Diuretics
      • Etacrynic acid
      • Furosemide
      • Thiazides
    • Sugar substitute
      • Mannitol
    • Calcium salts

Which diseases can reduce your magnesium level in the blood?

What can I do to increase magnesium blood levels?

If your magnesium level in the blood is a bit low you may raise it increasing your magnesium intake. Magnesium is found in many different foods

  • Vegetables: Spinach, artichokes, tomatoes
  • Nuts: Almonds, cashews and peanuts
  • Legumes: Beans
  • Others: Milk, chocolate, salmon

It is also recommended to reduce your alcohol intake.

If your doctor considers it appropriate he can prescribe you magnesium oral supplements.

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

You can visit our pages about:

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

The following values are considered to be below 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 hypomagnesemia
1.5 mg/dl1.4 mg/dl1.3 mg/dl1.2 mg/dl    
Moderate hypomagnesemia
1.1 mg/dl1 mg/dl0.9 mg/dl     
Marked hypomagnesemia
0.8 mg/dl0.7 mg/dl      
Severe hypomagnesemia
0.6 mg/dl0.5 mg/dl0.4 mg/dl0.3 mg/dl0.2 mg/dl0.1 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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