Rosh Emergency Medicine Practice Test

What effect does the initial medication administered for a patient with hyperkalemia have?

1. Eliminates potassium through the gastrointestinal tract

2. Promotes renal potassium excretion

3. Shifts potassium into the intracellular compartment

4. Stabilizes the resting membrane potential of the myocardial membrane

The correct answer is: Stabilizes the resting membrane potential of the myocardial membrane

In the context of treating hyperkalemia, the initial medication often administered is calcium, generally in the form of calcium gluconate or calcium chloride. The primary purpose of this administration is to stabilize the myocardial membranes. Hyperkalemia can lead to increased cardiac excitability and the risk of arrhythmias due to elevated potassium levels affecting the resting membrane potential of cardiac cells. By providing calcium, the drug helps to counteract these effects, reducing the risk of cardiac arrest. Calcium helps to stabilize the resting membrane potential by opposing the actions of potassium on the myocardial cells, thus making it less likely for the heart to enter dangerous arrhythmias. This protective effect is especially critical in acute settings where rapid interventions can be life-saving for patients experiencing the consequences of high serum potassium levels. While the other potential effects mentioned could play a role in the overall management of hyperkalemia, immediate stabilization of the cardiac membranes is the most critical action taken with the initial medication.