What Is Hypomagnesemia?

Too Little Magnesium in the Blood

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Hypomagnesemia refers to a lower-than-normal level of magnesium in the blood. When levels are too low, it can lead to problems like increased blood pressure, other kinds of cardiovascular disease, and even sudden death.

In the United States, hypomagnesemia affects roughly 2% of people. However, it is more common in people staying in the hospital, particularly those staying in the intensive care unit.

Magnesium blood test

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Symptoms of Hypomagnesemia

A person with hypomagnesemia might not have any symptoms if their magnesium is only slightly low, or they may have only mild symptoms. On the other hand, more severe hypomagnesemia is more likely to cause severe issues. Potential symptoms include:

  • Tiredness
  • Weakness
  • Tremor
  • Tingling or prickling sensations (paresthesia)
  • Chondrocalcinosis (causing joint pain)
  • Failure to gain weight normally (in children)
  • Abnormal muscle tightness
  • Increased blood pressure
  • Osteoporosis
  • Seizures

The condition can also cause problems with other electrolytes. For example, it may result in hypokalemia (low potassium), which can cause additional issues.

Hypomagnesemia further increases the risk of certain heart problems, including high blood pressure, coronary artery disease, and congestive heart failure. 

Changes in the heart rhythm are very serious potential symptoms. Sometimes visible on an EKG, they may make one prone to life-threatening abnormal heart rhythms. Coronary artery spasm is another potentially serious complication of severe hypomagnesemia.

Increased risks of premenstrual syndrome and certain psychiatric disorders are also found in people with low amounts of magnesium in their blood.

People who have type 2 diabetes and hypomagnesemia tend to have a more rapid progression of their disease. This increases the risk of complications from diabetes.

Causes

To understand the causes of hypomagnesemia, it’s important to first look at magnesium and its use in the body.

What Is Magnesium?

Magnesium is one of the body’s main minerals. Much of the magnesium in your body is present in your bones.

When dissolved in body fluids such as blood, magnesium is an electrolyte. Electrolytes are small ions that are integral to cellular function and all physiologic processes in our bodies. 

Magnesium is the fourth most common electrolyte in the body (after calcium, potassium, and sodium). Because of how electrolytes move through the body, changes in one electrolyte, like magnesium, may cause changes in others. 

Magnesium’s Roles

Magnesium plays many important roles in the body. It is part of several different enzymatic processes that trigger the many chemical reactions needed for life. 

For instance, magnesium plays a key role in the cardiovascular signaling in the heart. It is also needed to make:

  • DNA, which is needed when cells divide
  • RNA, which is important for making proteins 
  • ATP, which the body uses to store and transfer energy

So it’s not surprising that problems with magnesium may lead to symptoms in many different parts of the body.

Because of magnesium’s many important roles, your body normally regulates the amount of magnesium in your blood very carefully. If something causes this to get out of whack, you might develop hypomagnesemia, or less commonly, hypermagnesemia (elevated magnesium in the blood).

Dietary Deficiency

Magnesium deficiency usually only happens under special circumstances. People generally get enough magnesium from the water they drink and from certain foods. For example, magnesium is found in leafy greens, grains, nuts, and beans. 

However, sometimes people don’t get enough magnesium in their diet, which might happen if a person eats a lot of heavily processed foods. It also might be more likely if you drink water that is considered “soft”—meaning it is very low in magnesium and certain other electrolytes. 

Sometimes people might not get enough magnesium in their diet for other reasons, like alcohol use disorder. 

Hypomagnesemia can also occur when a person has been receiving nutrition through their veins (parenteral nutrition). If not carefully monitored, this can result in a condition called refeeding syndrome, in which electrolytes such as magnesium are very low.

Medical Conditions

Low levels of magnesium in the blood can happen for other reasons too. Certain medical conditions put you at risk of hypomagnesemia. 

For instance, you may also lose too much magnesium through the gastrointestinal tract or kidneys, or if you aren’t absorbing magnesium well. Some scenarios where this may happen include:

  • Diarrhea from a virus or bacterial infection
  • Diarrhea from a chronic condition (like Crohn’s disease)
  • Prolonged vomiting (like from a viral infection)
  • Celiac disease or other conditions causing poor absorption of foods
  • Pancreatitis
  • Complications of removal of the thyroid or parathyroid gland (hungry bone syndrome)
  • Complications of gastric bypass surgery
  • Complications from emergency treatment of diabetic ketoacidosis
  • Complications from kidney disease

Certain rare genetic diseases also can cause hypomagnesemia. Examples include Bartter syndrome and Gitelman syndrome.

Medications 

Using certain medications can put you at risk of hypomagnesemia. Proton pump inhibitors like Prilosec (omeprazole), which are used to treat problems like gastroesophageal reflux disease, are a common example.

Other medications that might cause hypomagnesemia include:

  • Diuretic drugs, like Lasix (furosemide) or Microzide (hydrochlorothiazide)
  • Aminoglycoside antibiotics, like Gentak (gentamicin)
  • Antifungals, like Abelcet (amphotericin B)
  • Calcineurin inhibitors, like Protopic (tacrolimus)
  • Certain chemotherapy drugs, like Erbitux (cetuximab)

Diagnosis

Sometimes a person might be found to have hypomagnesemia after they come to their doctor for certain symptoms. Other times a person might be dealing with a known medical condition, and they find out that they have hypomagnesemia as well. In either case, it’s important not just to diagnose hypomagnesemia, but also whatever is causing it.

A person’s medical history can give some clues. This includes recent symptoms and known medical conditions. For example, someone with prolonged diarrhea might be at risk of hypomagnesemia. Or hypomagnesemia might be more of a risk in someone on hemodialysis for kidney disease.

The medical history and clinical exam might lead a doctor to order certain blood tests, including blood tests for magnesium. Magnesium may be important to test in someone who is having unusual heart rhythms, as seen on an EKG.

Magnesium might also be checked in someone who has low levels of calcium (hypocalcemia) or potassium (hypokalemia).

People with kidney disease need to have their magnesium checked regularly. That can help make sure that the kidney isn’t either releasing too much through the urine or hanging onto too much magnesium.

Blood Tests for Magnesium

Hypomagnesemia is diagnosed through a blood test for magnesium (Mg2+). Someone with a concentration below 0.70 mM/L is defined as having low levels of magnesium in their blood.

Some researchers believe this value should be higher—0.85 mM or greater, especially for people with diabetes. By this definition, many more people would be found to have hypomagnesemia.

However, it’s a little confusing because a magnesium blood test doesn’t actually tell you the total magnesium in your body. That’s because most magnesium in a person’s body isn’t found in the blood. So a person might have low magnesium in their body but a normal value in their blood. 

In some cases, a person will need to be treated for low magnesium, even if their blood level of magnesium is in the normal range. This may be needed if they have clear signs and symptoms of magnesium deficiency and a reason for a magnesium deficiency is already known.

Diagnosing Underlying Causes

The problem causing the magnesium deficiency will sometimes be obvious from the medical context; other times more testing will be needed. The person’s symptoms and other medical problems will help guide this part of the diagnostic process. This might include further blood tests, imaging tests, or other tests, as needed.

Certain follow-up tests might also be advised. For example, checking an EKG might be a good idea for someone with hypomagnesemia, especially if the value is quite low. 

If you have diabetes, it may be worth asking your doctor to test for hypomagnesemia. If you have a low level and correct this, it might help you better manage your diabetes.

It may also be a good idea to get a blood test for magnesium if you have been taking a drug like Prilosec (omeprazole), which can lower these levels.

Treatment

Treatment for hypomagnesemia is oral magnesium or magnesium through an intravenous (IV) line. If a person’s blood magnesium is only slightly low, oral treatment is generally recommended. 

Oral magnesium is available in several different formulations. Some of the easiest to absorb are:

People generally respond well to oral treatment with magnesium. However, it can sometimes cause side effects like diarrhea, nausea, and vomiting.

For a more serious deficiency, your healthcare professional may seek to correct this more rapidly through an IV. This needs to be monitored carefully, however, as hypermagnesemia has its own serious health risks. 

Additionally, caution needs to be used for certain people. For example, people with kidney problems may be likely to develop hypermagnesemia (too high levels of magnesium) if they are given too much.

Addressing Electrolyte Abnormalities

Hypomagnesemia often occurs along with other electrolyte abnormalities, which may also need to be addressed. This might include oral calcium for hypocalcemia or oral potassium for hypokalemia. 

Addressing Underlying Medical Conditions

It’s also critical that the cause of the low magnesium be addressed. Depending on the context, this might include:

  • Change in a medication that is lowering your magnesium as a side effect
  • Dietary changes for a condition like celiac disease
  • Antibiotics for a bacterial infection causing vomiting or diarrhea

A Word From Verywell

Though not common, low magnesium levels in your blood are something to be aware of since they can impact so many health conditions.

The good news is, in most cases, low levels of magnesium can be easily addressed by taking oral magnesium and treating the underlying cause. Talk with your healthcare professional if you are experiencing any symptoms of concern.

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