A nurse is caring for a client who has heart failure and is prescribed furosemide. Which of the following laboratory values should the nurse monitor closely?

The nurse should monitor the serum potassium level to determine the therapeutic effectiveness of digoxin (Lanoxin), a cardiac glycoside that improves the contractility and pumping ability of the heart. Digoxin has a narrow therapeutic range and can cause toxicity if the serum level is too high or if the patient has hypokalemia (low potassium).Hypokalemia can result from diuretic therapy, which is often prescribed for heart failure patients to reduce fluid overload.

Therefore, the nurse should monitor the serum potassium level and report any abnormal values to the provider.The normal potassium level is 3.5 to 5.0 mEq/L.

Choice B) Serum sodium level is wrong because sodium level is not directly affected by digoxin therapy.

Sodium level may be altered in heart failure patients due to fluid retention or diuretic use, but it does not indicate the effectiveness of digoxin.

Choice C) Serum magnesium level is wrong because magnesium level is not directly affected by digoxin therapy.

Magnesium level may be altered in heart failure patients due to diuretic use or renal impairment, but it does not indicate the effectiveness of digoxin.

Choice D) Serum calcium level is wrong because calcium level is not directly affected by digoxin therapy.

Calcium level may be altered in heart failure patients due to renal impairment or vitamin D deficiency, but it does not indicate the effectiveness of digoxin.

The nurse should monitor the client’s serum potassium level closely because furosemide is a loop diuretic that can cause hypokalemia, which increases the risk of cardiac arrhythmias and digitalis toxicity. The nurse should also monitor the client’s fluid status, blood pressure, and renal function.

Choice B is wrong because Serum calcium is wrong because furosemide does not affect calcium levels significantly. Calcium levels are more likely to be affected by thiazide diuretics, which can cause hypercalcemia.

Choice C is wrong because Serum albumin is wrong because furosemide does not affect albumin levels significantly. Albumin levels are more likely to be affected by liver disease, malnutrition, or nephrotic syndrome.

Choice D is wrong because Serum glucose is wrong because furosemide does not affect glucose levels significantly. Glucose levels are more likely to be affected by diabetes mellitus, corticosteroids, or stress.

Normal ranges for the laboratory values are:

• Serum potassium: 3.5-5.0 mEq/L

• Serum calcium: 8.5-10.5 mg/dL

• Serum albumin: 3.5-5.0 g/dL

• Serum glucose: 70-110 mg/dL