What to know about a magnesium deficiency (hypomagnesemia)

People with mild hypomagnesemia may have no symptoms. If symptoms arise, they may include:

• twitches, particularly in the facial muscles
• weakness and exhaustion
• nausea and vomiting
• tremors
• constipation

A more severe magnesium deficiency can cause:

• muscle contractions
• seizures
• changes in the heart’s rhythm

In a 2019 review, researchers noted that low blood magnesium could increase the risk of cardiovascular disease and atrial fibrillation, a disorder that causes the upper heart chambers to become uncoordinated as they beat.

Magnesium deficiency is uncommon in typically healthy people.

A person may develop hypomagnesemia if:

• They consistently get too little magnesium from their diet.
• Their kidneys excrete too much magnesium.
• They have another medical condition that affects nutrient absorption.

Certain groups have a risk of magnesium inadequacy, which is a milder condition. This includes people affected by:

• Malnutrition: Starvation, anorexia, bulimia, or frequent vomiting for any reason can result in a magnesium deficiency.
• Digestive diseases: People with conditions such as Crohn’s disease, celiac disease, or regional enteritis can have difficulty absorbing magnesium via the gut.
• Diarrhea: Chronic diarrhea can lead to an imbalance of electrolytes and increase the risk of hypomagnesemia.
• Alcohol use: Excessive alcohol consumption can lead to imbalances in electrolytes or nutrients, and it may cause the body to release more magnesium than usual.
• Chestfeeding or pregnancy: Both increase the need for magnesium. During pregnancy, an adult’s magnesium needs to increase from 310–320 milligrams (mg) to 350–360 mg per day.
• Age: It becomes more difficult to absorb magnesium with time, putting older adults at a higher risk of magnesium inadequacy.
• Diabetes: If a person has type 2 diabetes or insulin resistance, high glucose levels in the kidneys can cause the body to excrete more magnesium.
• Organ failure: Organ failure, particularly of the kidneys, may cause the body to excrete too much magnesium.

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

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

Taking certain thyroid hormones may have a similar effect.

In the blood, normal serum magnesium levels range from 0.75 to 0.95 mmol/l. Doctors diagnose hypomagnesemia when an individual has a serum magnesium level of less than 0.75 mmol/l.

A blood test can confirm the diagnosis. If there is no apparent cause, the doctor can determine if the person is losing magnesium through their kidneys or digestive system. They can measure the amount of magnesium in the person’s urine over 24 hours.

Doctors treat low magnesium levels in different ways, depending on the situation.

Mild cases

A doctor may suggest getting more magnesium from the diet for mild magnesium inadequacy in people with no other health problems. The following foods contain high amounts of magnesium:

If eating magnesium-rich foods is not an option or does not help, a doctor may suggest a magnesium supplement. However, anyone with a kidney condition must use these with caution.

If the kidneys are not functioning well, they may not excrete any surplus magnesium at a typical rate, leading to the opposite problem — hypermagnesemia. This is when the body has too much magnesium.

Learn more about hypermagnesemia.

Severe cases

If someone has more significant hypomagnesemia, a doctor may treat it by giving a high dose of magnesium over a period of time.

If a person’s magnesium levels are persistently low, the underlying cause also requires treatment. For example, if the kidneys are losing too much magnesium, a doctor may recommend amiloride, a diuretic that increases urine output while sparing potassium and magnesium.

A person with very low levels of magnesium may also have a calcium or potassium deficiency. Low calcium is known as hypocalcemia, while a potassium deficiency is called hypokalemia.

Magnesium helps transport calcium and potassium ions in and out of cells. It may also contribute to the absorption of these important minerals. This is why a lack of magnesium can lead to low calcium and potassium levels.

The outlook for someone with a magnesium deficiency depends on the cause.

If a mild case of magnesium inadequacy results from factors such as a lack of magnesium in the diet, pregnancy, or older age, eating more magnesium-rich foods or taking a supplement can often resolve the issue.

For people with more severe or persistent hypomagnesemia, a doctor must identify the cause before they can predict the outcome. If they can find and treat the root cause, a complete recovery is likely.

Receiving treatment is crucial, as dangerously low levels of this mineral can cause fatal heart conditions. It is also important that people do not self-diagnose and treat a magnesium deficiency.

A person should not take magnesium supplements, especially in high doses, without speaking to a doctor. Too much of any nutrient, including magnesium, can be harmful and cause an imbalance in levels of other nutrients.

What happens if magnesium is low?

A person’s symptoms will depend on the severity of their magnesium deficiency. Symptoms include:

• nausea
• loss of appetite
• fatigue
• muscle contractions
• seizures

What is the most common cause of hypomagnesemia?

Hypomagnesemia has many potential causes, including:

• excessive alcohol use
• inadequate diet
• chronic diarrhea
• excessive urination, such as in uncontrolled diabetes
• medication side effects

When to go to the ER for low magnesium?

Magnesium deficiency can lead to severe and potentially fatal complications without treatment. If a person exhibits symptoms of hypomagnesemia, they should seek medical help immediately.

What is critical low magnesium?

Hypomagnesemia is defined as a blood serum magnesium level of less than 0.75 mmmol/l.

Hypomagnesemia is the medical term for magnesium deficiency. This is defined as a blood magnesium level of less than 0.75 mmol/l.

Magnesium deficiencies are rare in healthy people but may occur due to malnutrition, nutrient absorption disorders, dehydration, diabetes, and alcohol use.

Treatment for hypomagnesemia depends on the cause and the severity of the condition. Untreated hypomagnesemia can lead to severe complications. As such, timely diagnosis and medical intervention are crucial to improving outcomes.