HESI Registered Nurse EXIT Practice Exam

What is the most common cause of hypokalemia in patients taking diuretics?

1. Excess potassium intake

2. Inadequate dietary intake of potassium

3. Fluid retention

4. Increased renal potassium elimination

The correct answer is: Increased renal potassium elimination

The primary cause of hypokalemia in patients taking diuretics is increased renal potassium elimination. Diuretics, especially loop and thiazide diuretics, work by promoting the excretion of sodium and water from the kidneys. As a consequence of this process, potassium, which is also excreted through the renal system, is lost in larger amounts. This mechanism leads to a decrease in serum potassium levels, resulting in hypokalemia, which can have significant clinical implications, such as muscle weakness, cramping, and abnormal heart rhythms. Although inadequate dietary intake of potassium is a factor that can contribute to hypokalemia, it is less significant in patients who are already losing potassium through renal excretion due to diuretic use. Fluid retention does not directly lead to hypokalemia but rather indicates the opposite condition. Excess potassium intake does not cause hypokalemia and would not be a relevant factor in this scenario. Therefore, understanding that the primary action of diuretics is to increase the renal excretion of potassium clarifies why increased renal potassium elimination is the most common cause of hypokalemia in patients taking these medications.