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Care During Chemotherapy and Beyond

Hypermagnesemia (High Magnesium)



What Is Hypermagnesemia?

Hypermagnesemia is an electrolyte imbalance and is indicated by a high level of magnesium in the blood.  The normal adult value for magnesium is 1.5-2.5 mEq/L.   

Magnesium is one of many electrolytes in your body. Normal levels of magnesium are important for the maintenance of heart, and nervous system function.

What Causes Hypermagnesemia?

Your body regulates magnesium levels by shifting magnesium into and out of cells.  When there is a breakdown or destruction of cells, the electrolyte magnesium moves from inside the cell, to outside of the cell wall.  This shift of magnesium outside of the cells causes hypermagnesemia.

Magnesium is excreted by your kidneys. Any damage to your kidneys, when they are not working properly, may cause an increase in magnesium levels.

Other causes of hypermagnesemia include:

  • Increased destruction or shift of potassium from within the cells. As seen with Tumor Lysis Syndrome, when you receive chemotherapy, the drugs will act by breaking down the tumor cells. When there is a rapid amount of cellular destruction, the components of the cells (including magnesium and potassium), will move outside of the cell and into the blood stream. People who receive chemotherapy for Leukemia, Lymphoma, or multiple Myeloma, may be at risk for Tumor Lysis Syndrome, if there is a large amount of disease present.
  • Decreased excretion of potassium from your body.
  • Renal (kidney) failure is the most common cause of magnesium excess.  Your kidneys are not able to process and excrete magnesium and other electrolytes.
  • You may be taking in too much magnesium in your diet, usually in the form of laxatives (such as milk of magnesia), or antacids.

What Are Some Symptoms of HypermagnesemiaTo Look For?

You may not have any symptoms, unless your blood magnesium levels are significantly elevated. You may have muscle weakness, confusion, and decreased reflexes if your blood test results show severely low blood magnesium levels.

Things You Can Do If Your Blood Test Results Indicate Hypermagnesemia:

  • Follow your healthcare provider's instructions regarding lowering your blood magnesium level. If your blood levels are severely elevated, he or she may prescribe medications to lower the levels to a safe range.
  • Take all of your medications as directed if blood test results show you have hypermagnesemia. Avoid laxatives and antacids containing magnesium if your kidneys are not working properly.
  • If you are constipated:
    • Make sure to keep active, and keep your bowels moving!
    • Increase your daily intake of fresh fruit and fiber. Prunes, and prune juice may work for some individuals. It is important to move your bowels daily.
    • If you do not move your bowels every day, your health care provider may prescribe stool softeners and laxatives to help prevent constipation, not containing magnesium if you have kidney problems. Work with your healthcare provider to develop a regimen that will work for you. 
    • Drink 2 to 3 liters of fluid every 24 hours, unless you were told to restrict your fluid intake. This will decrease your chances of being dehydrated, which can lead to constipation.
  • Follow all of your healthcare provider's recommendations for follow up blood work and laboratory tests. 
  • Avoid caffeine and alcohol, as these can cause you to have electrolyte disturbances.

Drugs That May Be Prescribed By Your Doctor For Hypermagnesemia:

  • Calcium - This medication is given usually intravenously, to lower the blood magnesium level, if you have severely high blood magnesium levels.
  • Hemodialysis - If you have a severely elevated blood magnesium level, and you are currently in kidney failure, your healthcare provider and a kidney specialist may order dialysis treatments.

When To Call Your Doctor or Health Care Provider About Hypermagnesemia:

  • Nausea that interferes with your ability to eat, and is unrelieved by prescribed medication.
  • Vomiting (vomiting more than 4-5 times in a 24 hour period).
  • Severe constipation, unrelieved by laxatives, lasting 2 to 3 days.
  • Muscle weakness, poor appetite that does not improve.
  • Feeling your heart beat rapidly (palpitations).

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Note:  We strongly encourage you to talk with your health care professional about your specific medical condition and treatments. The information contained in this website is meant to be helpful and educational, but is not a substitute for medical advice.