Podcast 1016: Hypokalemia

Contributor: Meghan Hurley, MD

Educational Pearls:

What is hypokalemia?

• Hypokalemia is when the measured blood level of potassium falls below 3.5 mEq/L (normal 3.5 - 5.2 mEq/L).

• Can generally be considered in mild (3.0 - 3.5 mEq/L); moderate (2.5 - 2.9 mEq/L); and severe (<2.5 mEq/L) categories with differing treatment goals based on levels.

• Should be noted that blood levels of potassium can be low while total body potassium is normal due to intracellular shift by certain agents like β-2 agonists (e.g. Albuterol) or insulin. There is no appreciable loss of insulin despite hypokalemia being present in labs.

What are the most common causes of hypokalemia?

• Medications are a predominant cause; mainly loop and thiazide diuretics.

• Gastrointestinal losses such as prolonged emesis or diarrhea (can occur in the setting of chronic illness and treatment such as chemotherapy patients with emesis).

• Other renal losses (e.g. hyperaldosteronism and renal tubular acidosis).

• A fun-fact renal loss: A compound found in some licorice (Glycyrrhizic acid) can inhibit 11-ß-hydroxysteroid dehydrogenase enzyme type 2 and cause mineralocorticoid excess. See a 2023 case study in references for Lethal Arrhythmia Induced by Licorice.

What is a less common cause of hypokalemia?

• Hypokalemic Periodic Paralysis (HypoPP) is a genetic autosomal dominant channelopathy where patients leak potassium at rest causing a flaccid paralysis of muscle.

• Typically impacting legs more than arms, and proximal muscles more than distal muscles.

• Can be triggered carbohydrate rich meals, rest after exercise, febrile illness, and fasting.

• Male predominance, typically in early adulthood.

• Treatment is avoidance of triggers and supplementation with conservative oral potassium to avoid overcorrection during attacks.

What are some symptoms and findings associated with hypokalemia?

• Patients may present with generalized weakness and fatigue.

• Highly crucial to monitor for EKG changes in the setting of hypokalemia.

• May notice flattening of T wave with the development of a U wave at certain potassium levels. The lower the potassium levels, the more likely a TU fusion can be seen.

• Prolongs QT interval which puts patients at risk for lethal arrhythmias.

What are treatment considerations for hypokalemia?

• At milder levels of hypokalemia that are asymptomatic and a reversible cause is identified, oral repletion via potassium tablets should be considered. Patients may be a candidate to complete their course of treatment in the Emergency Room.

• At higher symptomatic levels with distinct EKG changes, more aggressive repletion (including IV Potassium) should be considered. Patients may be candidates for admission.

• Always monitor and replace magnesium levels as well, as they tend to follow potassium levels as well.

• Consider intracellular shifts as a source of hypokalemia to avoid risk of overcorrection into hyperkalemia.

• Hypokalemia can cause deadly heart rhythms such as ventricular fibrillation and ventricular tachycardia including Torsades Des Pointes that will be refractory to defibrillation. Treatment considerations at this point include:

• Consideration of esmolol

• Double Sequential Defibrillation

• Extracorporeal Membrane Oxygenation (ECMO).

Key takeaways?

• Hypokalemia is most often associated with medication side effects or total volume loss from emesis or diarrhea. Depending on the degree of hypokalemia, different treatment considerations must be made. Monitor patient EKG closely for changes that can progress to lethal arrhythmias.

References:

1. Yannopoulos D, Bartos J, Raveendran G, et al. Advanced reperfusion strategies for patients with out-of-hospital cardiac arrest and refractory ventricular fibrillation (ARREST): a phase 2, single centre, open-label, randomised controlled trial. Lancet. 2020;396(10265):1807-1816. doi:10.1016/S0140-6736(20)32338-2

2. Cheskes S, Verbeek PR, Drennan IR, et al. Defibrillation Strategies for Refractory Ventricular Fibrillation. New England Journal of Medicine. 2022;387(21):1947-1956. doi:10.1056/NEJMoa2207304

3. Oswald S, Ravioli S, Schwarz C, Lindner G. Hypokalaemia in the emergency department: aetiology, diagnosis, and management. Swiss Medical Weekly. 2026;156(4):4767-4767. doi:10.57187/4767

4. Gao Z, Xing H, Zhang J, Chen S, Gao Z. Hypokalemic periodic paralysis: novel perspectives from genetic mutations to clinical management. Gene. 2026;999:150172. doi:10.1016/j.gene.2026.150172

5. Han EJ, Park JS. Lethal Arrhythmia Induced by Licorice. J Korean Med Sci. 2023;38(12):e107. doi:10.3346/jkms.2023.38.e107

6. Lee YH, Lee KJ, Min YH, et al. Refractory ventricular fibrillation treated with esmolol. Resuscitation. 2016;107:150-155. doi:10.1016/j.resuscitation.2016.07.243

Summarized by Dan Orbidan, OMS3 | Edited by Dan Orbidan & Ahmed Abdel-Hafiz, NREMT-P

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