Electrolyte imbalances: Safe medication practices in the management of potassium disturbances

By Monica Elzawy, Rinko Lau, and Certina Ho

Potassium

Potassium is an electrolyte that is essential for normal body functions, including muscle contraction, nerve signaling, and heart function. Potassium imbalances occur when potassium levels are too low (also known as hypokalemia) or too high (also known as hyperkalemia). These imbalances may or may not present symptoms, which may include fatigue, muscle weakness, muscle cramps, constipation, heart palpitations, and/or tingling sensations in the limbs. In more severe cases, potassium imbalances may cause life-threatening heart rhythm disturbances and require urgent treatment. Since many medical- and medication-related factors could affect potassium levels, identifying at-risk patients, prescribing safely, and monitoring potassium levels appropriately are important steps in preventing complications and reducing harm. Readers can learn more about adult normal lab values (including potassium) at https://mcc.ca/examinations-assessments/resources-to-help-with-exam-prep/normal-lab-values/ and the role of potassium in our body health.

Hypokalemia (Low Potassium Level)

Mild to moderate hypokalemia may be asymptomatic or may present symptoms, such as fatigue, muscle weakness, constipation, cramping, or heart palpitations. Severe hypokalemia could be life-threatening with symptoms such as heart rhythm disturbances and respiratory failure. 

Hypokalemia can happen due to medical conditions that are associated with increased potassium loss, reduced potassium intake, shifting of potassium from blood to cells, or loss of magnesium, etc. Common medication-related causes may include the use of thiazide and loop diuretics, laxatives, insulin, and beta-agonists. Other contributors include gastrointestinal and renal losses of potassium, such as via diarrhea, vomiting, and metabolic alkalosis, respectively.

Management of hypokalemia focuses on identifying and treating the underlying cause(s) while safely correcting potassium levels. Mild cases or asymptomatic patients are often managed using oral potassium replacement and addressing contributing factors, such as identifying medications that may be associated with an increase in potassium loss. More severe or symptomatic cases may need intravenous potassium replacement and close monitoring, especially, for cardiac arrhythmias. Typically, throughout the management of hypokalemia, both potassium and magnesium levels, as well as renal and heart functions will be monitored. Readers can learn more about management of acute hypokalemia in adults at https://www.sps.nhs.uk/articles/hypokalaemia/.

Hyperkalemia (High Potassium Level)

Mildly elevated potassium levels may not be associated with any symptoms. Severe hyperkalemia may lead to clinical manifestations like cardiac arrythmias or muscle weakness.

Hyperkalemia can occur due to increased potassium intake, or reduced elimination of potassium (for instance, due to renal impairment). Metabolic acidosis or injury to cells may cause a shift of potassium from cells to blood, leading to an elevated level. Among the classes of medications which may contribute to hyperkalemia are, for example, potassium-sparing diuretics, angiotensin-converting enzyme inhibitors (ACEIs), angiotensin-II receptor blockers (ARBs), nonsteroidal anti-inflammatory drugs (NSAIDs), and certain antibiotics (e.g., trimethoprim). Learn more about drug-induced hyperkalemia

The approach to managing hyperkalemia will depend on the severity of the condition, its associated symptoms, and the contributing factors of high potassium levels. It may include cardiac stabilization, potassium shift from blood to cells, and potassium elimination. Learn more about management of hyperkalemia 

• Cardiac stabilization – The initial step in managing elevated potassium levels is to discontinue any external source(s) of potassium and treat the underlying cause. Since potassium plays an important role in heart health, an electrocardiogram (ECG) may be used for close monitoring of the heart. If ECG changes are observed, the cardiac cell membranes can be stabilized with intravenous calcium.

• Potassium shift – Shifting potassium from blood to cells could be achieved with the use of intravenous insulin and beta agonists. Insulin is usually administered with dextrose to prevent hypoglycemia (low glucose level), and glucose levels will also be monitored.

• Potassium elimination – Potassium can be removed from the body by using loop diuretics (e.g., furosemide), potassium binders, or dialysis (for patients with end-stage kidney disease or severe renal impairment).

What can patients do?

Electrolytes, such as potassium, play an essential role in our health. Electrolyte imbalances can be induced by medical- and/or medication-related factors. Patients should be well informed by their healthcare providers regarding their medical condition(s) and why they are on certain medications and their associated benefits and potential risks (e.g., side effects). When patients see their primary care clinicians during regular or follow-up appointments and at times of patient consultation at the pharmacy, they may consider using the Institute for Safe Medication Practices Canada (ISMP Canada) “5 Questions to Ask About Your Medications” to help initiate a dialogue with healthcare professionals and understand when monitoring of electrolytes may be needed.

Monica Elzawy is a PharmD graduate from the Leslie Dan Faculty of Pharmacy, University of Toronto; Rinko Lau is a PharmD student at the Leslie Dan Faculty of Pharmacy, University of Toronto; and Certina Ho is an Assistant Professor, Teaching Stream, at the Leslie Dan Faculty of Pharmacy and Department of Psychiatry, University of Toronto.

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