A nurse in a provider's office is monitoring blood electrolytes for four clients who take digoxin.
Which of the following electrolyte values increases a client's risk for digoxin toxicity?
Potassium 3.0 mEq/L.
Calcium 9.2 mg/dL.
Sodium 140 mEq/L.
Magnesium 2.2 mg/dL.
The Correct Answer is A
This is because low potassium levels (hypokalemia) increase the sensitivity of the heart to digoxin and can lead to toxicity even with normal serum digoxin levels. Digoxin inhibits the sodium-potassium pump on the cardiac cells, which causes potassium to accumulate outside the cells. Low potassium levels in the blood create a larger gradient for potassium to move out of the cells, which enhances the effect of digoxin and can cause arrhythmias.
Choice B is wrong because calcium 9.2 mg/dL is within the normal range (8.5 to 10.2 mg/dL) and does not increase the risk of digoxin toxicity. However, high calcium levels (hypercalcemia) can potentiate the effects of digoxin and cause toxicity.
Choice C is wrong because sodium 140 mEq/L is within the normal range (135 to 145 mEq/L) and does not increase the risk of digoxin toxicity. However, high sodium levels (hypernatremia) can reduce the binding of digoxin to the sodium-potassium pump and decrease its efficacy.
Choice D is wrong because magnesium 2.2 mg/dL is within the normal range (1.7 to 2.4 mg/dL) and does not increase the risk of digoxin toxicity. However, low magnesium levels (hypomagnesemia) can increase the sensitivity of the heart to digoxin and cause toxicity.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Propranolol is a beta-blocker that can cause bronchoconstriction and worsen asthma symptoms.
Asthma is a reversible airway disease that is a contraindication for taking propranolol.
Choice A, tachycardia, is not a contraindication for taking propranolol.In fact, propranolol can be used to treat some types of tachycardia, such as atrial fibrillation or supraventricular tachycardia, by slowing down the heart rate.
Choice C, hypertension, is not a contraindication for taking propranolol.Propranolol can be used to treat hypertension by reducing the cardiac output and peripheral resistance.
Choice D, glaucoma, is not a contraindication for taking propranolol.Propranolol does not affect the intraocular pressure or the aqueous humor production.However, some other beta-blockers, such as timolol, can be used to treat glaucoma by lowering the intraocular pressure.
Correct Answer is C
Explanation
Digoxin is a cardiac glycoside that increases the force of heart contractions (positive inotropy) and decreases the heart rate (negative chronotropy) by inhibiting the sodium-potassium ATPase pump in the cardiac cell membranes and affecting the autonomic tone.This helps to improve the symptoms of heart failure and to control the ventricular rate in atrial fibrillation.
Choice A is wrong because positive chronotropy means increasing the heart rate, which is the opposite of what digoxin does.
Choice B is wrong because negative inotropy means decreasing the force of heart contractions, which is also the opposite of what digoxin does.
Choice D is wrong because positive inotropy and positive chronotropy would both increase the workload of the heart, which is not desirable in heart failure or atrial fibrillation.
Normal ranges for digoxin are 0.5 to 2 ng/mL for heart failure and 0.8 to 2 ng/mL for atrial fibrillation.Digoxin has a narrow therapeutic window and can cause serious side effects if overdosed or underdosed.
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