What should the nurse closely monitor in a patient being treated with furosemide (Lasix)?

Monitoring potassium levels in a patient treated with furosemide (Lasix) is crucial because furosemide is a loop diuretic that promotes the excretion of sodium, water, and potassium in the urine. Unlike some other diuretics, such as thiazides, loop diuretics can lead to significant potassium loss, resulting in hypokalemia (low potassium levels). This condition can cause serious cardiac issues, including arrhythmias, muscle weakness, and increased risk of digitalis toxicity if the patient is also taking digoxin.

Regular assessment of potassium levels allows healthcare providers to take necessary actions, such as dietary recommendations or potassium supplementation, to prevent complications associated with low potassium. Close monitoring ensures the patient's electrolyte balance is maintained throughout their treatment.