A client on a medication regimen including diuretics expresses concerns about potassium levels. Which medication should the nurse monitor closely?

Bumetanide is a loop diuretic, which primarily acts on the renal tubules to promote the excretion of sodium and water. A significant effect of loop diuretics, including bumetanide, is the increased excretion of potassium, which can lead to hypokalemia (low potassium levels) in patients. Because of this pharmacologic property, it is crucial for the nurse to closely monitor potassium levels in patients taking bumetanide to prevent complications associated with low potassium, such as muscle weakness, arrhythmias, or electrolyte imbalances.

In contrast, the other medications listed do not have this same primary action that would necessitate close monitoring of potassium levels. Candesartan is an angiotensin receptor blocker, which can have a mild potassium-sparing effect in some cases but also has risks for hyperkalemia. Carvedilol is a beta-blocker that does not affect potassium levels significantly. Isosorbide is a nitrate used for angina relief and does not influence potassium homeostasis either. Therefore, the primary concern regarding potassium levels and the need for monitoring is specifically associated with the use of bumetanide.