Electrolyte Imbalance

Electrolytes are chemicals in the body that regulate important physiologic functions. Examples of electrolytes are sodium, chloride, magnesium, potassium, and calcium. Electrolyte imbalance causes a variety of symptoms that can be severe. Electrolyte imbalance is commonly caused by loss of body fluids through prolonged vomiting, diarrhea, sweating, or high fever. The most serious forms of electrolyte imbalance in cancer patients include high blood calcium levels, called hypercalcemia, or a disorder called tumor lysis syndrome, which results in electrolyte imbalance from the killing of cancer cells. Both of these can be life threatening if not managed appropriately.

Functions of Electrolytes and Their Normal Ranges

*Values may vary from laboratory to laboratory.

What causes electrolyte imbalance?

Electrolyte imbalance is commonly caused by loss of body fluids through prolonged vomiting, diarrhea, sweating, or high fever. All of these may be side effects of chemotherapy treatment.

The kidneys play a critical role in regulating electrolytes. They control the levels of chloride in your blood and “flush out” potassium, magnesium, and sodium. Therefore, a disturbance in blood levels of these electrolytes may be related to kidney function.

What are the symptoms of electrolyte imbalance?

An electrolyte imbalance may lead to a number of symptoms that depend on which electrolytes are out of balance and whether the level is too high or too low. If you have altered potassium, magnesium, sodium, or calcium levels, you may experience one or more of the following symptoms:

• Muscle spasm
• Bone disorders
• Weakness
• Blood pressure changes
• Twitching
• Irregular heartbeat
• Numbness
• Nervous system disorders
• Confusion
• Convulsions
• Lethargy
• Seizures

Which electrolyte disorders are most serious for cancer patients?

Hypercalcemia - A high level of calcium in the blood, called hypercalcemia, may become a medical emergency. This disorder is most commonly caused by cancer or parathyroid disease. Hypercalcemia resulting from cancer is particularly common in conjunction with breast cancer, lung cancer, or multiple myeloma and often results from the destruction of bone due to bone metastases.

Signs and symptoms of hypercalcemia may include:

• Nausea
• Fatigue
• Vomiting
• Lethargy
• Stomach pain
• Moodiness
• Constipation
• Irritability
• Anorexia
• Confusion
• Excessive thirst
• Extreme muscle weakness
• Dry mouth or throat
• Irregular heart beat
• Frequent urination
• Coma

These many signs and symptoms are commonly attributed to either the cancer treatment or the cancer itself and may make it difficult for doctors to detect hypercalcemia when it first occurs. This disorder can be severe and difficult to manage. Severe hypercalcemia is a medical emergency requiring immediate treatment.

Tumor lysis syndrome - When cancer cells are killed by therapy, they may spill their inner (intracellular) contents, which accumulate in the body faster than can be eliminated. These excess intracellular contents cause the metabolic and electrolyte disturbances that result in tumor lysis syndrome (TLS). TLS can result in life-threatening complications if not managed appropriately. If TLS is untreated, its progression may cause acute kidney failure, cardiac arrhythmias, seizures, loss of muscle control, or death.

Some patients with TLS may have initial symptoms including:

• Nausea and vomiting
• Joint discomfort
• Shortness of breath
• Irregular heartbeat
• Lethargy
• Cloudy urine

Other patients feel no symptoms of TLS in its early stages, but have abnormal laboratory results. Laboratory results indicative of TLS show high potassium, uric acid, and phosphorous levels and low calcium levels in the blood.

Patients at a high risk of developing TLS typically have acute leukemia or lymphoma that is very responsive to chemotherapy. Patients with pre-existing kidney dysfunction are also at an increased risk of developing TLS.

Patients who are considered to be at risk of developing TLS are typically treated with preventive measures before and during their treatment for cancer. Preventive measures typically include intravenous hydration, medications including allopurinol or Elitek® (rasburicase), and alkalinization of the urine with sodium bicarbonate.

Once TLS has actually developed, a patient is also treated for the specific medical abnormality that is present, which typically includes one or more of the following:

• High uric acid (hyperuricemia)
• High potassium (hyperkalemia)
• High phosphate (hyperphosphatemia)
• Low calcium (hypocalcemia)