Electrolytes — What are they? What happens if you don't have enough?

Physician holding sign that reads electrolytes

A woman in her 40s was facing one of the most challenging times of her life. Diagnosed with an aggressive form of breast cancer, she embarked on a rigorous chemotherapy treatment. However, she started feeling unusually fatigued and weak. Simple tasks she used to manage effortlessly now seemed daunting. She couldn't shake off the persistent muscle cramps that had begun to plague her legs, causing considerable discomfort.

Blood tests revealed a significant drop in her potassium levels, a condition known as hypokalemia. Potassium, an essential electrolyte, plays a crucial role in muscle and nerve function, including regulating heartbeat. The chemotherapy had inadvertently disrupted the balance, causing her potassium levels to drop, a potentially serious but manageable side effect.

To resolve the symptoms, her treatment plan was adjusted and she was prescribed potassium supplements to restore her electrolyte balance. In addition, she was counseled to maintain a balanced diet that included potassium-rich foods like bananas, potatoes and leafy greens, and to make sure she consumed enough fluid for adequate hydration.

What are electrolytes?

Electrolytes, such as sodium, potassium and calcium, are molecules that carry an electric charge and are essential for various physiological processes in your body. Electrolytes are dissolved in bodily fluids, such as blood and cellular fluids, and play a crucial role in maintaining proper cell function, nerve impulses, muscle contractions and fluid balance.

  • Regulate the fluid levels in your blood plasma and your body.
  • Keep the pH (acid/alkaline) of your blood in the normal range (7.35-7.45, slightly alkaline).
  • Enable muscle contractions, including the beating of your heart.
  • Transmit nerve signals from heart, muscle and nerve cells to other cells.
  • Help blood to clot.
  • Help build new tissue.

How does cancer affect my electrolytes?

Cancer treatments can disrupt these electrolyte balances in several ways:

  • Chemotherapy. Many chemotherapy drugs can have toxic effects on the kidneys, which are responsible for regulating electrolyte levels in the body. Damage to the kidneys can impair their ability to properly excrete and retain electrolytes, leading to imbalances.
  • Radiation therapy. Radiation therapy, particularly when used near vital organs like the kidneys or salivary glands, can damage these structures. This damage can interfere with their electrolyte-regulating functions.
  • Nausea and vomiting. Chemotherapy-induced nausea and vomiting can lead to excessive fluid loss, which can upset the balance of electrolytes in the body. Frequent vomiting can cause the loss of potassium, sodium and chloride, leading to imbalances.
  • Diarrhea. Certain cancer treatments, including chemotherapy and radiation therapy, can irritate the gastrointestinal tract and lead to diarrhea. Prolonged or severe diarrhea can result in the loss of electrolytes, particularly potassium and sodium, which are vital for normal cell function.
  • Dehydration. You may experience dehydration due reduced fluid intake, fever, or increased fluid loss from treatments like radiation therapy. Dehydration can disrupt electrolyte balance by concentrating electrolyte levels in the blood.
  • Medications. Some medications used to address side effects can directly affect electrolyte levels or interact with other medications in ways that disrupt electrolyte balance.
  • Nutritional changes. Cancer treatments can affect your appetite and ability to eat and digest food. Malnutrition can impact electrolyte levels, as you may not receive an adequate supply of essential minerals from your diet.

To ensure that you have enough electrolytes, stay hydrated and eat foods rich in electrolytes, including spinach, turkey, potatoes, beans, avocados, oranges, soybeans (edamame), strawberries and bananas.

With the exception of sodium, it's unlikely you'll have an excessive amount of electrolytes in your body from your diet alone. (The risk may be higher if your kidneys are not working well.) However, supplements can cause problems — for example, too much calcium can increase your risk of kidney stones — so always talk to your doctor before you start to take them.

*Processed foods and restaurant meals can be very high in sodium.

Normal Range* Notes
Sodium Na+


Older folks with chronic illness who have low sodium will have more symptoms than younger, healthy people with the same low sodium level.

Chloride Cl-


May not have symptoms unless level changes are severe. Since it is closely tied to sodium, some people have symptoms of hyponatremia (low sodium levels in the blood).

Potassium K+


Works with sodium to maintain water balance and acid/base balance. With calcium, it regulates nerve and muscle activity.

Magnesium Mg+2


Mostly in bones, with about 1% in extracellular fluid (body fluid outside the cells). Important for enzyme reactions.

Calcium Ca+2


99% in teeth and bones. Calcium in blood is ionized (carries an electrical charge) and helps regulate cell function, heart rate and blood clotting. The body needs vitamin D to absorb calcium. (Ionized calcium level range is 4.7-5.28.)

Phosphate/Phosphorus PO4-


Blood tests measure inorganic phosphate. About 85% is in bones; most of the rest is inside cells. Phosphate helps build/repair bones and teeth, stores energy, contracts muscles and enables nerve function. The body needs vitamin D to absorb phosphorus.

*Ranges may vary by lab.

Electrolytes to know about


Low sodium, also called hyponatremia, causes water to move into cells. High sodium, or hypernatremia, causes fluid to move out of the cells. When either of these things happens in brain cells, it can cause personality changes, headache, confusion and lethargy. If the sodium drop is severe, it can result in seizures, coma and death. A key symptom of hypernatremia is thirst.


Low chloride (hypochloremia) may be due to excessive vomiting, suctioning of stomach contents, or “loop” diuretic medications, often used to treat fluid retention caused by heart or kidney problems or high blood pressure. High chloride (hyperchloremia) often results from diarrhea or kidney disease.

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Low potassium (hypokalemia) may not cause symptoms, but it may affect how your body stores glucogen (your muscles’ source of energy) or cause abnormal heart rhythms. A level under 3 milliequivalents per liter (mEq/L)can cause muscle weakness, spasms, cramps, paralysis and respiratory problems. If it continues, kidney problems may occur. High potassium (hyperkalemia) may not cause any symptoms, although you may experience muscle weakness or abnormal heart rhythms. If the level goes very high, the heart can stop beating.


Low calcium (hypocalcemia) may not cause symptoms, but chronically low levels can cause changes in skin, nails and hair; yeast infections; and cataracts. As levels drop, muscle irritability and cramps (particularly in legs and back) may develop. Calcium under 7 milligrams per deciliter (mg/dL)causes changes in your reflexes (hyperreflexia), muscle spasms, spasms of the larynx (voice box) and seizures. High calcium (hypercalcemia) may not cause symptoms. As calcium rises, constipation, loss of appetite, nausea, vomiting, abdominal pain, neuromuscular symptoms and bowel obstruction (ileus) may occur. Above 12 mg/dL, emotional swings, confusion, delirium and stupor occur. Above 18 mg/dL, it may result in shock, kidney failure and death. Persistent or severe hypercalcemia can damage the kidneys and cause heart problems, including rhythm changes and heart attacks.


Low magnesium (hypomagnesemia) may cause symptoms similar to low potassium or calcium. An extremely low level can be life-threatening. High magnesium (hypermagnesemia) may cause low blood pressure, breathing problems (slow, ineffective breathing) and heart problems (cardiac arrest).


Low phosphate (hypophosphatemia) can cause muscle weakness, respiratory failure, heart failure, seizures and coma. It may be caused by very poor nutrition, certain diuretic medications, diabetic ketoacidosis (DKA), alcoholism and severe burns. DKA is a serious complication of diabetes in which cells burn fat instead of glucose. This creates ketones, which enter the blood and turn it acidic. Normal blood is slightly alkaline. High phosphates (hyperphosphatemia) may not cause symptoms. It may be due to tumor lysis syndrome, overwhelming infection, chronic kidney disease, parathyroid gland disorder, or acidosis (blood pH more acidic than normal).