Hypermagnesemia

Overview

Hypermagnesemia means there is too much magnesium in your blood. Magnesium is a mineral your body needs for muscles, nerves, and a steady heartbeat. Healthy kidneys usually remove extra magnesium in urine. High levels happen when the kidneys cannot remove magnesium well, or when extra magnesium gets into the body from supplements, laxatives, antacids, or treatment given in hospital.

It is uncommon in healthy people. Mild high magnesium is more often found on blood tests in people who have kidney problems, are in hospital, or use products that contain magnesium.

It most often affects people with kidney disease, people in hospital who receive magnesium through a vein, older adults, and people who often use magnesium-containing laxatives or antacids. It can also affect children, especially those with kidney problems or accidental ingestion of magnesium products.

Symptoms

Common symptoms

• Often no symptoms when the level is only mildly high
• Nausea or vomiting
• Feeling weak or very tired
• Drowsiness or unusual sleepiness
• Flushing or feeling warm
• Low blood pressure, which can cause dizziness
• Slow heartbeat
• Confusion
• Reduced reflexes, such as feeling slower to react

Symptoms in children

• Poor feeding
• Vomiting
• Floppiness or poor muscle tone
• Unusual sleepiness
• Weak cry
• Slow breathing

Symptoms in older adults

• Confusion or new memory problems
• Dizziness or falls
• Weakness
• Low blood pressure
• Slow pulse
• Worsening kidney function

Causes

Main causes

• Kidney problems, especially kidney failure, because the kidneys cannot remove extra magnesium
• Taking in too much magnesium from supplements, laxatives, or antacids that contain magnesium
• Receiving magnesium through a vein in hospital
• Some hormone problems, such as an underactive thyroid or adrenal gland problems
• Dehydration or low blood volume
• Bowel problems that change how much magnesium the body absorbs

Risk factors

• Having kidney disease or kidney failure
• Being older, especially with reduced kidney function
• Dehydration
• Using magnesium-containing supplements, laxatives, or antacids often
• Receiving magnesium through a vein in hospital
• Having certain hormone or bowel conditions
• Taking several medicines without a regular review by a clinician or pharmacist

When to see a doctor

See a doctor urgently if:

• You have new confusion, severe weakness, or extreme sleepiness
• You have repeated vomiting or cannot keep fluids down
• You have very little or no urine
• You feel dizzy or faint when standing
• You have a slow heartbeat and feel unwell

Book a routine appointment if:

• You have kidney disease and use magnesium-containing supplements, laxatives, or antacids
• You have mild muscle weakness, nausea, or tiredness that does not settle
• You want to review your supplements or over-the-counter medicines
• You have been told before that your magnesium level was high

Diagnosis

A blood test is the main way to diagnose hypermagnesemia. Your clinician will also look for the cause by asking about your diet, supplements, laxatives, antacids, kidney history, and medicines. In more serious cases, they may check your heart rhythm and monitor you in hospital.

Tests that may be done

• Blood test for magnesium level
• Blood tests for kidney function and other electrolytes (minerals in the blood)
• Electrocardiogram (ECG) to check the heart's rhythm
• Review of medicines, supplements, and diet
• Urine tests sometimes

What to expect at your appointment

You will usually have a blood sample taken. If your magnesium level is high, your clinician may repeat the test and check how your kidneys are working. They may also do a heart tracing. If the level is very high or you feel unwell, you may need to be watched in hospital while the cause is treated.

Treatment

Treatment depends on how high the magnesium level is and what is causing it. The first step is usually to stop any source of extra magnesium. Mild cases may only need review and repeat blood tests. More serious cases need hospital care with close monitoring of breathing, blood pressure, and heart rhythm.

Self-care at home

• Do not take magnesium supplements unless your clinician advises it
• Check labels on supplements, antacids, and laxatives for magnesium
• Do not stop or change prescribed medicines without asking your clinician or pharmacist
• Drink enough fluids unless your clinician has told you to limit them
• Keep appointments for blood tests and reviews
• Tell every clinician and pharmacist about all products you use

Medical treatments

In hospital, clinicians may stop any magnesium-containing products and give fluids through a vein. They may monitor your heart and breathing closely and use treatments that help your kidneys remove extra magnesium. In severe cases, a filtering treatment called dialysis may be needed. The care team will also treat the underlying cause, such as kidney problems or dehydration.

When is surgery considered?

Surgery is not used to treat hypermagnesemia. In severe cases, a filtering treatment called dialysis may be used, but this is not surgery.

Living with this condition

If you are at risk of high magnesium, regular checkups and medicine reviews can help keep you safe. Keep a list of all supplements, antacids, laxatives, and prescribed medicines, and show it to your clinician or pharmacist. Ask before starting any new over-the-counter product.

Lifestyle tips

• Check product labels for magnesium
• Avoid self-prescribed magnesium supplements
• Keep kidney problems managed with your care team
• Stay hydrated unless told otherwise
• Ask your pharmacist to review all medicines and supplements
• Keep blood test appointments if you have kidney disease

Diet and exercise

A balanced diet that includes normal magnesium-rich foods is usually fine unless your clinician tells you otherwise. Do not cut out healthy foods on your own. Gentle activity helps general health, but ask your care team about safe exercise if you feel weak or are recovering in hospital.

Mental health and emotional wellbeing

Hearing that you have high magnesium can be worrying, especially if you are in hospital or have kidney disease. It is okay to feel anxious. Talk with your care team, family, or a counselor. If you feel overwhelmed or unsafe, contact local crisis support or emergency services right away.

Prevention

Often yes. Many cases can be prevented by not taking magnesium products unless advised, checking labels, and monitoring magnesium levels in people with kidney disease. Regular medicine reviews can also help.

Vaccines

There is no vaccine for hypermagnesemia. Vaccines are still important for general health, so ask your clinician which ones are recommended for you.

Screening programmes

There is no routine screening for everyone. Blood magnesium may be checked if you have kidney disease, are in hospital, or use products that can raise magnesium.

Complications

If left untreated

• Dangerously slow or irregular heartbeat
• Very low blood pressure and fainting
• Slow or stopped breathing
• Coma
• Cardiac arrest (the heart stops)
• Worsening kidney problems

Long-term outlook

Most people recover well when the cause is found and treated. Mild cases often cause no lasting problems. Severe cases need hospital care, but treating the cause and monitoring the heart and breathing can greatly improve the outlook.

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