Magnesium is an essential mineral that plays a vital role in many functions in the body. It helps regulate muscle and nerve function, blood sugar levels, blood pressure, and bone health. Most people get enough magnesium from their diet, but magnesium deficiency is possible. On the other end of the spectrum, it’s also possible to get too much magnesium. This is known as hypermagnesemia.
While magnesium toxicity is rare, it can occur, especially in people with impaired kidney function. The kidneys are responsible for filtering excess magnesium from the blood. When they cannot adequately do this job, magnesium levels build up. Some medications, like magnesium-containing antacids and laxatives, can also cause high magnesium levels when taken in excess.
So what happens when magnesium levels get too high? Here is an overview of the common symptoms and complications.
Signs and Symptoms
Mild to moderate hypermagnesemia generally does not cause obvious symptoms. It takes significantly elevated magnesium levels before symptoms typically appear.
According to research, symptoms generally do not manifest until blood magnesium levels surpass 3 mEq/L. To put this into context, normal serum magnesium levels range from 1.5 to 2.5 mEq/L.
Here are some of the most common signs and symptoms of severely elevated magnesium levels:
Muscle Weakness
One of the classic signs of hypermagnesemia is generalized muscle weakness. Magnesium plays an important role in muscle contractions. At normal levels, it allows muscles to relax after a contraction.
When magnesium is high, it overactivates this process. It prevents the muscles from fully contracting and relaxing, leading to weakness. This effect on the muscles can also cause cramps, tremors, and spasms.
Respiratory Effects
High magnesium has significant effects on the respiratory system. The most dangerous complication is respiratory paralysis or arrest. This occurs because magnesium causes muscles in the diaphragm and chest wall to weaken.
Magnesium toxicity can impair breathing patterns. Shortness of breath, a slow respiratory rate, and even complete respiratory failure can happen in severe cases.
Low Blood Pressure
Hypermagnesemia typically causes vasodilation, meaning it widens blood vessels. This leads to low blood pressure, also known as hypotension.
When blood pressure drops significantly, it reduces blood flow to vital organs like the brain. Hypotension can cause dizziness, lightheadedness, fainting, and even shock.
Reduced Nerve Function
High magnesium levels affect neurotransmitters, which are chemicals that send signals throughout the nervous system. Neurotransmitter dysfunction can suppress nerve impulses.
This can cause numbness, tingling sensations, and muscle weakness. In severe toxicity, it may progress to paralysis. Loss of deep tendon reflexes is also common.
Mental Status Changes
Nerve and brain function relies heavily on maintaining the right balance of electrolytes like magnesium. When magnesium levels get very high, it starts to have toxic effects on the brain.
Confusion and disorientation are common early signs. More extreme toxicity can lead to hallucinations, delirium, and even coma. Seizures are also possible.
Irregular Heartbeat
Magnesium is important for maintaining a normal heart rhythm and conduction of nerve impulses through the heart. Hypermagnesemia can disrupt this electrical activity.
Irregular heartbeats such as atrial fibrillation, heart block, and other arrhythmias may develop. Severely high magnesium levels can even cause cardiac arrest.
Kidney Failure
The kidneys play a key role in regulating magnesium balance in the body. Their ability to filter and excrete excess magnesium prevents toxic accumulation.
In hypermagnesemia, the high magnesium itself can damage kidney tubules. This impairs their filtering capacity. Kidney failure allows magnesium to build up further, creating a vicious cycle.
Other Symptoms
A few other possible symptoms of elevated magnesium levels include:
– Nausea, vomiting and loss of appetite
– Flushing, sweating
– Lightheadedness upon standing
– Headache
– Changes in urine output
– Low calcium levels
Risk Factors
Certain individuals are at higher risk of developing hypermagnesemia. Risk factors include:
Kidney Disease
Chronic kidney disease and acute kidney injury or failure are perhaps the biggest risk factors. The kidneys filter about 2400mg of magnesium per day. Impaired kidney function reduces this crucial excretion pathway.
Older Age
Kidney function tends to decline gradually with age. Elderly people are therefore more prone to high magnesium levels, especially when taking magnesium-containing medications.
Diabetes
Poorly controlled diabetes can damage the kidneys over time. Diabetics are also more likely to use magnesium-based laxatives and antacids. Both reasons increase their risk.
Excess Magnesium Intake
Consuming extremely high amounts of magnesium through diet, supplements or medications can overwhelm the kidneys. This allows magnesium to accumulate.
Sources leading to toxicity may include:
– Magnesium salts used as antacids or laxatives
– Magnesium supplements, especially magnesium oxide which is poorly absorbed
– Over-the-counter Epsom salt baths
– Magnesium injections given in high doses
Critical Illness
Severely ill patients in intensive care are more prone to electrolyte disturbances. Hypermagnesemia can develop due to medications, kidney failure, or low blood pressure during illness.
Hypothyroidism
Low thyroid hormone levels affect kidney function and magnesium excretion, raising risk of toxicity.
Adrenal Insufficiency
Diseases impairing the adrenal glands can reduce magnesium excretion. Addison’s disease is one example.
When to See a Doctor
Mildly elevated magnesium generally doesn’t cause symptoms. But if you experience any signs of toxicity, promptly contact your healthcare provider.
Seeking medical care is especially important if you have conditions or take medications that may raise your risk. Be sure to mention the use of any magnesium-containing over-the-counter products.
In cases of severe hypermagnesemia, emergency medical care is crucial. Call 911 or go to the nearest emergency room if you or a loved one has signs like:
– Severe muscle weakness
– Respiratory distress
– Sudden change in mental status or confusion
– Fainting, dizziness or extremely low blood pressure
– Chest pain or irregular heartbeat
– Seizure
Rapid treatment can prevent life-threatening complications relating to heart or respiratory failure.
Diagnosis
Doctors can diagnose high magnesium levels with a simple blood test. Normal serum magnesium levels are considered to be:
– Adults: 1.5 to 2.5 mEq/L
– Children: 1.5 to 2.3 mEq/L
– Newborns: 1.5 to 2 mEq/L
Significantly elevated levels above the normal range indicate hypermagnesemia. Levels are considered severely high at greater than 4 mEq/L, when symptoms are most likely.
Along with testing magnesium, doctors will also check kidney function through blood tests. Impaired kidney function is a likely cause of magnesium buildup.
Other electrolytes like calcium and potassium will also be evaluated, as their balance is important. Low calcium, for example, can exacerbate magnesium toxicity effects.
Treatment
Treatment focuses on reducing magnesium levels while managing symptoms:
Discontinue Magnesium Intake
Doctors will advise stopping magnesium-containing medications, supplements, antacids and laxatives. This can help prevent further accumulation.
Improve Kidney Function
Treating any underlying kidney disorders or problems can enhance magnesium excretion and lower levels.
Increase Magnesium Excretion
Drugs that promote magnesium excretion through the urine, like furosemide, are sometimes given. Dialysis can also filter out excess magnesium from the blood.
Give Intravenous Calcium
Calcium helps counteract the effects of magnesium toxicity on muscles and nerves. Administering calcium intravenously can quickly provide relief from symptoms.
Provide Respiratory Support
In severe toxicity with respiratory depression, endotracheal intubation and mechanical ventilation may be required.
Treat Low Blood Pressure
Giving intravenous fluids can help improve low blood pressure. Medications to increase blood pressure may also help counter shock.
Correct Other Electrolyte Abnormalities
Restoring balance of electrolytes like potassium is important to stabilize the heart and muscles. Potassium levels often drop in hypermagnesemia.
Prevention
You can take these steps to avoid developing high magnesium levels:
– Avoid excessive use of magnesium supplements or magnesium-containing antacids and laxatives. Only take at recommended dosages.
– Stay well hydrated to avoid magnesium concentrations building up.
– Have kidney function monitored if at higher risk of toxicity.
– Inform your doctor about any over-the-counter magnesium products you take.
– Get blood work periodically to check magnesium levels if you have kidney disease, take magnesium medications, or have signs of toxicity.
– Follow dosage guidelines carefully if you need magnesium infusions for a medical procedure.
Outlook
Mild hypermagnesemia often causes minimal or no symptoms. The prognosis is good when magnesium levels are brought back down into the normal range.
However, severely elevated magnesium can potentially be life-threatening. Toxicity can cause respiratory or cardiac arrest in extreme cases. Rapid treatment is critical to support breathing and heart function.
With intensive care and monitoring, the outlook for severe hypermagnesemia can be favorable. But in certain high-risk groups, like those with chronic kidney failure, high magnesium may be difficult to manage long-term.
Conclusion
Magnesium is an important mineral that plays many roles in the body. But too much magnesium can be dangerous. Hypermagnesemia is generally only seen when kidney function is impaired. However, excessive use of magnesium-containing products can also push levels too high.
Signs of toxicity include muscle weakness, respiratory depression, low blood pressure, numbness and changes in mental status. Seeking prompt medical care for symptoms is crucial.
Doctors can treat elevated magnesium levels through IV fluids, medications, dialysis and other measures. Avoiding magnesium excess and monitoring levels in at-risk individuals can help prevent toxicity.