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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Vitamin K is the antidote for warfarin toxicity because it can reverse the effects of warfarin by restoring the clotting factors.Warfarin is an oral anticoagulant that works by inhibiting vitamin K epoxide reductase, an enzyme that activates vitamin K in the body.Vitamin K is needed for the synthesis of active coagulation factors, such as II, VII, IX and X.By blocking vitamin K, warfarin reduces the blood’s clotting activity and prevents the formation of blood clots.
Choice A is wrong because vitamin B12 is not involved in the coagulation cascade.Vitamin B12 is mainly involved in DNA synthesis, red blood cell production and nerve function.
Choice C is wrong because calcium gluconate is not an antidote for warfarin toxicity.Calcium gluconate is used to treat low blood calcium levels or hypocalcemia.Calcium is also a cofactor for some coagulation factors, but it does not reverse the effects of warfarin.
Choice D is wrong because protamine sulfate is not an antidote for warfarin toxicity.
Protamine sulfate is used to reverse the effects of heparin, another type of anticoagulant that works by inhibiting thrombin and factor Xa.
Protamine sulfate does not affect the vitamin K-dependent coagulation factors that are inhibited by warfarin.
Normal ranges for coagulation tests that are affected by warfarin are:
• Prothrombin time (PT): 11 to 13.5 seconds
• International normalized ratio (INR): 0.8 to 1.2
• Activated partial thromboplastin time (aPTT): 25 to 35 seconds
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.
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