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 carvedilol (Coreg), which is a beta-blocker that can lower the heart rate and blood pressure. Carvedilol can also cause hyperkalemia, which is a high level of potassium in the blood that can lead to cardiac arrhythmias and muscle weakness.Therefore, the nurse should monitor the serum potassium level and report any values above 5.0 mEq/L to the provider.
Choice B) Serum sodium level is wrong because carvedilol does not affect the sodium level significantly.Sodium level is more relevant for diuretics, which can cause hyponatremia (low sodium) or hypernatremia (high sodium) depending on the type and dose of the medication.
Choice C) Serum magnesium level is wrong because carvedilol does not affect the magnesium level significantly.
Magnesium level is more relevant for digoxin, which is another medication used for heart failure that can cause hypomagnesemia (low magnesium) or hypermagnesemia (high magnesium).Hypomagnesemia can increase the risk of digoxin toxicity, while hypermagnesemia can decrease the effectiveness of digoxin.
Choice D) Serum calcium level is wrong because carvedilol does not affect the calcium level significantly.
Calcium level is more relevant for calcium channel blockers, which are another class of medications used for heart failure that can lower the heart rate and blood pressure by blocking the entry of calcium into the cardiac and vascular smooth muscle cells.
Calcium channel blockers can cause hypocalcemia (low calcium) or hypercalcemia (high calcium), which can affect the cardiac contractility and conduction.
The normal ranges for serum electrolytes are:
• Potassium: 3.5 to 5.0 mEq/L
• Sodium: 135 to 145 mEq/L
• Magnesium: 1.5 to 2.5 mEq/L
• Calcium: 8.5 to 10.5 mg/dL
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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