A patient with atrial fibrillation has been prescribed digoxin (Lanoxin). The nurse should monitor which laboratory value to evaluate therapeutic effectiveness?
Serum potassium level
Serum sodium level
Serum magnesium level
Serum calcium level.
The Correct Answer is A
Digoxin (Lanoxin) is a cardiac glycoside that is used to treat atrial fibrillation and heart failure.
It works by increasing the force of cardiac contraction and slowing down the heart rate.
However, digoxin can also cause toxicity, which can lead to life-threatening arrhythmias.
One of the risk factors for digoxin toxicity is hypokalemia, or low serum potassium level.
Potassium is an electrolyte that is essential for normal cardiac function and conduction. When the serum potassium level is low, digoxin binds more strongly to the cardiac cells and increases its effects, which can result in bradycardia, heart block, or ventricular tachycardia.
Therefore, the nurse should monitor the serum potassium level to evaluate the therapeutic effectiveness and safety of digoxin therapy.
Choice B) Serum sodium level is wrong because sodium is not directly related to digoxin action or toxicity.
Sodium is another electrolyte that is important for fluid balance and blood pressure regulation. However, sodium does not affect the binding of digoxin to the cardiac cells or its effects on the heart rate and contractility.
Therefore, the nurse does not need to monitor the serum sodium level to evaluate digoxin therapy.
Choice C) Serum magnesium level is wrong because magnesium is not directly related to digoxin action or toxicity.
Magnesium is another electrolyte that is involved in many enzymatic reactions and neuromuscular function. However, magnesium does not affect the binding of digoxin to the cardiac cells or its effects on the heart rate and contractility.
Therefore, the nurse does not need to monitor the serum magnesium level to evaluate digoxin therapy.
Choice D) Serum calcium level is wrong because calcium is not directly related to digoxin action or toxicity.
Calcium is another electrolyte that is essential for bone health and muscle contraction. However, calcium does not affect the binding of digoxin to the cardiac cells or its effects on the heart rate and contractility.
Therefore, the nurse does not need to monitor the serum calcium level to evaluate digoxin therapy.
The normal range for serum potassium level is 3.5-5.0 mEq
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
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.
Correct Answer is B
Explanation
The correct answer is choice B. “I can walk farther without getting tired.” This statement indicates a therapeutic effect of metoprolol, which is a beta-blocker that reduces the heart rate, blood pressure, and the workload of the heart.This helps to improve the blood flow and oxygen delivery to the heart and other organs, and reduces the symptoms of heart failure such as fatigue, dyspnea, and edema.
Choice A is wrong because “I have less swelling in my ankles.” This statement indicates a possible effect of a diuretic, which is a medication that reduces fluid retention and edema by increasing urine output.Metoprolol does not have a direct diuretic effect, although it may indirectly reduce fluid accumulation by improving cardiac function.
Choice C is wrong because “I don’t have chest pain anymore.” This statement indicates a possible effect of a nitrate, which is a medication that dilates the blood vessels and reduces the oxygen demand of the heart.Metoprolol may also help to prevent or treat angina by lowering the heart rate and blood pressure, but it is not the primary medication for chest pain relief.
Choice D is wrong because “I can breathe better at night.” This statement indicates a possible effect of an oxygen therapy, which is a treatment that delivers supplemental oxygen to the lungs and improves gas exchange.Metoprolol may also help to reduce dyspnea by improving cardiac function and reducing pulmonary congestion, but it is not the primary treatment for respiratory distress.
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