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 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
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
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