Magnesium Deficiency: Low Magnesium Levels in the Blood

A magnesium deficiency is the presence of low magnesium levels in the blood. In this article, we'll explain what the causes are and how it's treated.
Magnesium Deficiency: Low Magnesium Levels in the Blood
Leonardo Biolatto

Written and verified by the doctor Leonardo Biolatto.

Last update: 27 May, 2022

Doctors consider a magnesium deficiency to be when the amount of magnesium in the blood is lower than what is considered normal (between 1.7 mg/dL and 2.2 mg/dL). Based on these figures, magnesium deficiency refers to cases where laboratory results are lower than 1.7 mg/dL. These are considered low magnesium levels.

If you want to know why low magnesium levels occur and what the symptoms are, we invite you to continue reading!

Magnesium in the body

Magnesium is a cation or, in other words, an element with a positive electrical charge. Among the cations in the human body, it’s the most abundant outside the cell. In turn, inside the cells, it’s the second most abundant (after potassium).

As for the tissues where it’s present, we find most of the magnesium in our bones. Then, we find about 20% in the muscles, and the rest is distributed in other organs.

Diet and the elimination of urine regulate the amount of magnesium in the body. Thus, in a normal and varied diet, there are 360 milligrams of magnesium, which is enough to support the normal functioning of the body.

The foods that provide the most magnesium to the human body are cereals, nuts, and legumes. There is also magnesium in green leafy vegetables and seafood, such as shellfish.

Causes of magnesium deficiency

Experts Joel Michels Topf and Patrick T. Murray explain four main causes of hypomagnesemia:

  • Reduced intake: This is a rare and infrequent cause of this disorder. When magnesium intake decreases, the renal system has difficulty retaining it. It can occur when there are states of malnutrition or chronic alcoholism. Similarly, hypomagnesemia is an adverse effect in people eat who are fed parenterally (by vein) and not orally.
  • Great losses: If the digestive system isn’t able to retain and absorb the magnesium that enters with food, the result is magnesium deficiency. Diarrhea, for example, could cause a decrease in absorption.

Read on: Nutrition and Kidney Failure: Everything You Need to Know

  • Hyperparathyroidism: As Helbert Rondón-Berríos explains, people suffering from this condition suffer from what we know as “redistribution of magnesium”. As there’s a deficit of parathormone (a hormone that increases calcium in the blood), this affects the metabolism of magnesium. This way, the bones retain it but it’s not present in the blood.
  • Renal dysfunction: As the balance of magnesium depends on its renal excretion, when there are pathologies in the kidneys there can also be hypomagnesemia. In fact, there’s a genetic condition -Gitelman Syndrome- in which children are born with an alteration of the renal tubules that prevents them from retaining potassium, calcium, and magnesium.

Symptoms of hypomagnesemia

In most cases, hypomagnesemia doesn’t produce symptoms on its own. The signs that become evident are the result of other associated substances. Therefore, the main symptom producer is the lack of potassium that low magnesium levels bring.

A variety of potassium sources surrounding a small chalkboard with the word "potassium" written on it.

Keep on discovering: 6 Foods that Contain More Potassium than Bananas

Once the body is deficient in magnesium and potassium, likely, calcium will also decrease. Hypocalcemia then adds to the symptoms as well.

This is how specialist James L. Lewis details the following clinical picture:

  • Nausea and vomiting
  • Weakness and tiredness
  • Anorexia: Lack of appetite
  • Muscle tremors: These can be small, such as severe twitching or spasms
  • Tetanic symptoms: The result of an extreme contracture of the muscles
  • Convulsions: According to several researchers at the University Hospital of Getafe, alterations in the internal blood environment can also alter the nerve transmission of the neurons

The treatment of low magnesium levels

If the hypomagnesemia isn’t severe and only shows up in a routine test, the treatment is simple. In this case, doctors recommend a diet with foods containing magnesium, to begin with. Then, they will discover the underlying cause of the disorder.

If there’s no improvement in blood magnesium values despite diet changes, a doctor will prescribe supplements. Oral supplements are always preferable.

Likewise, the parenteral route of the application of magnesium is for severe cases (with symptoms that affect the quality of life). However, it’s also chosen by patients who can’t use the oral route, e.g. because of digestive surgery. Also, chronic alcoholics with hypomagnesemia often prefer this route.

If hypomagnesemia is accompanied by low potassium or low blood calcium, these should also be treated. This was demonstrated by a study published by the Journal of Clinical Rheumatology in 2008.

In fact, ideally, all substances should be supplemented because if only one value is improved (e.g. potassium) without correcting the others, the effect isn’t long-lasting.

Combating low magnesium levels

If you have low magnesium levels in your blood, your health care professional will advise you on a suitable diet and treatment. By simply complying with these measures, the disorder should disappear.

Also, remember to maintain a healthy lifestyle and watch out for any symptoms to prevent these kinds of problems in time.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.