High Potassium Levels (Hyperkalemia) in Cancer

Symptoms, causes, and treatment of cancer-induced hyperkalemia

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What should you know about high potassium (hyperkalemia) during cancer treatment?. Istockphoto.com/Gab13

Hyperkalemia, or high potassium levels, are a common occurrence in people with cancer and can be life threatening.  What is the definition, what are the symptoms and causes, and how is this treated?


A high potassium level (hyperkalemia) is an electrolyte abnormality that may occur for several reasons in people with cancer. To better understand why potassium levels are important and what may cause them to increase or decrease, it's helpful to know how electrolytes function in the body.

Most people are familiar with electrolytes from Gatorade or Pedialyte commercials that stress rehydration after exercise (or vomiting and diarrhea in Pedialyte's case) to balance our electrolyte levels. While the information contained in the commercials is factual, it doesn't even begin to define the complexity of electrolytes and how critical they are to the body.

Understanding Electrolytes

In the most simple terms, electrolytes are compound minerals that when dissolved in water separate into electrically charged ions. There are many types of electrolytes, but sodium, potassium, chloride, bicarbonate, calcium, sulfate, magnesium and phosphate are considered the most important in the human body. Our bodies depend on electrolytes for muscle contraction (including the heart), nerve impulses, maintenance of fluid balance, and much more.

Through hormones, specialized mechanisms, and transporters, the kidneys are responsible for monitoring the concentration and volume of electrolytes and water in the body.

A basic example of how the kidneys regulate water and electrolytes is urination. When the body has excess fluid, urine output is increased. When the body is dehydrated, urine output is decreased. An excess of electrolytes is expelled from the body through urine, sweat, and the digestive tract. The kidneys have a strict margin of what is considered a low or high level of water or electrolytes in the body.

When levels increase or decrease, the kidneys begin responding immediately. Experiencing thirst is a basic example of how our body responds to decreased water levels.

In addition to potassium, monitoring for other electrolyte abnormalities, such as hypercalcemia in cancer patients is important during chemotherapy.


There are several factors that can contribute to increased potassium levels in people with cancer. Some of these include:

  • Tumors that produce hormones (paraneoplastic syndromes)
  • Chemotherapy side effects
  • Tumor lysis syndrome - About 98% of potassium in the body is found within cells, with only around 2% present in the bloodsteam.  In some cases, tumors are extremely responsive to chemotherapy.  The cancer cells die quickly and in large quantities.  When a cancer cell dies in this way, the contents of the electrolytes that were contained in the cell are essentially emptied into the bloodstream.  Ordinarily the kidneys and liver do a good job at eliminating excess potatssium, but this drastic influx of potassium can overload the body's ability to process it, resulting in dangerously high levels in the blood
  • Adrenal metastases (cancer spread to the adrenal glands)
  • Blood transfusions
  • People with cancer can also develop high potassium for reasons that people without cancer do, for example, from kidney failure and side effects of medications.

In people with cancer, it's important to make sure, as well, that what is being found is true hyperkalemia.  Pseudohyperkalemia (a level that looks high but isn't in actuality) can occur in patients with a very high white blood cell or platelet count.  With pseudohyperkalemia the serum potassium level is significantly higher than the plasma potassium level.


Potassium plays an important role in heart and neuromuscular function, so when levels are high, the heart, nerves, and muscles are often affected.

With mild elevations of potassium, you may not have any symptoms, but as levels increase symptoms may include:

  • Muscle weakness, spasms, and even paralysis
  • Shortness of breath and hyperventilation
  • Tingling sensations
  • Heart arrhythmias (irregular heart rhythms) are one of the more serious complications
  • Confusion
  • Seizures, coma, and death when the levels are very high


Hyperkalemia is diagnosed through blood tests and/or EKG's. The normal adult value for potassium is 3.5-5.3 mEq/L.  Some oncologists prefer labs done using plasma due to the possibility of pseudohyperkalemia as noted above.


Most of the time hyperkalemia is mild and can be treated by simply restricting potassium in the diet and treating the underlying cancer.  If it is more severe, treatment options may include:

  • Diuretics (water pills)
  • Intravenous glucose and insulin
  • IV calcium
  • Potassium absorbing medications
  • Dialysis

It's important to make sure that an elevated potassium level is true hyperkalemia) see above, and to keep in mind that hypokalemia (a low potassium level) can be extremely serious as well.

It's also important to avoid taking supplements.  In people without cancer, using supplements has sometimes been a cause of hyperkalemia, and taking vitamins and minerals during cancer treatment can sometimes interfere with the goals of treatment.


Larson, R., and C. Pui. Tumor lysis syndrome: Prevention and treatment. Updated 11/02/15. http://www.uptodate.com/contents/tumor-lysis-syndrome-prevention-and-treatment

Meng, Q., and E. Wagar. Pseudohyperkalemia: A new twist on an old phenomenon. Critical Reviews in Clinical Laboratory Science. 2015. 52(2):45-55.

Wilson, R., and J. Berns. Tumor lysis syndrome: new challenges and recent advances. Advances in Chronic Kidney Disease. 2014. 21(1):18-26.