USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

Which group of medications can lead to hyperkalemia by causing the inability of potassium to move intracellularly?

1. Digitalis, insulin, abuterol

2. NSAIDs, acetaminophen, diphenhydramine

3. Heparin, warfarin, clopidogrel

4. Amoxicillin, ciprofloxacin, doxycycline

The correct answer is: Digitalis, insulin, abuterol

The group of medications that can lead to hyperkalemia by causing the inability of potassium to move intracellularly includes digitalis, insulin, and albuterol. Digitalis works primarily by inhibiting the sodium-potassium ATPase pump, which can disrupt the normal movement of potassium into cells. This disruption reduces the intracellular uptake of potassium and contributes to elevated serum potassium levels. Insulin normally promotes the uptake of potassium into cells by stimulating the sodium-potassium ATPase pump. However, in situations where insulin is deficient or its action is impaired, such as in diabetes or certain types of stress, the intracellular movement of potassium can be inhibited, leading to hyperkalemia. Albuterol, a beta-2 adrenergic agonist, typically promotes the movement of potassium into cells. Nevertheless, in cases where there is an acute response to albuterol (like excessive dosing or in the presence of certain pathophysiological states), its effect can be altered, leading to inadequate potassium shifting and contributing to hyperkalemia. Together, these medications highlight the importance of intracellular shifts of potassium. When their function or delivery is disrupted, the normal balance of potassium is compromised, leading to hyperkalemia. The other groups listed, such as NSAIDs, anticoagulants