Hypomagnesemia: What to know about low magnesium

If left untreated, hypomagnesemia can cause chronic health problems and decrease the body’s levels of calcium and potassium.

In this article, we take a close look at what factors can cause low levels of magnesium. We also explore the effects on the body and methods of treatment.

What is hypomagnesemia?

Magnesium is a mineral and electrolyte that has a number of vital roles in the body. Because the body cannot produce it, magnesium must be consumed as part of a person’s diet.

According to the National Institutes of Health, an estimated 50–60 percent of the body’s magnesium is stored in the bones, and less than 1 percent is found in the blood.

Detecting a deficiency can be difficult, as it is not part of routine blood work.

Results of a 2012 study suggest that around 48 percent of Americans do not get enough magnesium in their diets. However, it is relatively uncommon for low magnesium intake to cause symptoms in healthy people.

Magnesium plays a role in more than 300 of the body’s enzyme reactions. It contributes significantly to the:

  • health of muscles and nerves
  • regulation of blood pressure
  • production of energy in the body’s cells
  • synthesis of DNA and RNA

Hypomagnesemia can occur when a person does not absorb enough magnesium from their diet. Or, they may release too much magnesium from the kidneys or through the gastrointestinal tract.

Malnutrition, possibly caused by anorexia, bulimia, or frequent vomiting can result in a magnesium deficiency. However, malnutrition is unlikely to be responsible for low levels of the mineral in otherwise healthy people.

Other causes of a magnesium deficiency include:

  • Alcoholism. Excessive alcohol consumption can lead to imbalances of electrolytes or nutrients, and it may cause the body to release more magnesium than usual.
  • Breast-feeding and pregnancy. These factors increase the need for magnesium.
  • Diarrhea. Chronic diarrhea can lead to an imbalance of electrolytes. People with related conditions such as Crohn’s disease are more vulnerable to hypomagnesemia.
  • Age. As a person ages, it becomes more difficult to absorb magnesium.
  • Diabetes. High levels of glucose in the kidneys can cause the body to release more magnesium. People with type 2 diabetes or insulin resistance may develop magnesium deficiencies. Diabetic ketoacidosis is a life-threatening complication of diabetes, and it can reduce magnesium levels.
  • Organ failure. Organ failure, particularly of the kidneys, may cause the body to excrete too much magnesium.

People on certain medications may also lose large amounts of magnesium. These medicines include:

  • some antifungal drugs
  • diuretics
  • proton pump inhibitors
  • the chemotherapy drug cisplatin

Individuals receiving the hormone vasopressin or certain thyroid hormones may be similarly affected.


When a magnesium deficiency causes symptoms, a doctor will usually prescribe supplements.

The following foods are also rich in this electrolyte:

  • almonds, peanuts, and cashews
  • other legumes and nuts
  • avocados
  • brown rice
  • oatmeal

When deficiencies are severe, or the methods above are ruled out, a doctor may recommend oral magnesium salts. Magnesium can also be injected into a muscle or vein. Ongoing monitoring can determine whether the treatment is working.

A magnesium deficiency is linked to other mineral deficiencies, and a doctor may treat them at the same time. For example, it is common to receive calcium and magnesium together.

It is important also to treat any underlying condition, such as diabetes, that could be responsible for low magnesium. A magnesium deficiency can indicate that the current treatment is not working. An improved treatment plan may include lifestyle changes or new medication.

Links with hypocalcemia and hypokalemia

A person with very low levels of magnesium may also have a calcium deficiency, called hypocalcemia, and a potassium deficiency, called hypokalemia.

Magnesium helps to transport calcium and potassium ions in and out of cells. It may also contribute to the absorption of these important minerals.

Treating only a magnesium deficiency can make a calcium deficiency worse because magnesium binds to calcium. Doctors who suspect hypomagnesemia will often test for other deficiencies at the same time.

A doctor may suspect that magnesium levels are low based on symptoms, or because a person has a condition commonly linked to a magnesium deficiency.

A blood test can confirm the diagnosis, and it is important that a doctor also check levels of calcium and potassium.

However, because most magnesium is located in the bones or tissues, a person may still have a deficiency, even when levels in the blood are normal. A person with a calcium or potassium deficiency may still need treatment for hypomagnesemia.


Most people with low levels of magnesium are unable to absorb the right amounts. Others may see improvement by adding magnesium-rich foods to the diet.

Foods that contain large amounts of both magnesium and calcium, such as milk and cheese, may provide more benefits.

Many people with a magnesium deficiency will never know it. When symptoms develop, immediate treatment is required. The deficiency is easily reversed, and a person may be surprised by how quickly their symptoms improve.

It is important, however, not to self-diagnose a magnesium deficiency and begin supplementation without seeing a doctor. Too much of any nutrient, including magnesium, can be harmful and may cause an imbalance in other minerals.

Speak with a doctor about any symptoms of hypomagnesemia.

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