NCLEX-RNReduction of Risk PotentialMedium
A client taking digoxin for heart failure reports nausea and seeing yellow halos around lights. Before administering the next dose, the nurse should prioritize checking which laboratory value?
- ASerum glucose
- BSerum sodium
- CBlood urea nitrogen
- DSerum potassium
Show answer & explanationAnswer & explanation
Correct answer: D. Serum potassium
Hypokalemia increases the risk of digoxin toxicity by enhancing the drug's binding to myocardial cells, and the client's symptoms (nausea, visual halos) suggest toxicity is already occurring. The nurse must check potassium before giving another dose, since low potassium potentiates digoxin's toxic effects on the heart.
Why the other options are wrong
- A. Glucose is unrelated to digoxin toxicity.
- B. Sodium does not directly affect digoxin toxicity risk.
- C. BUN reflects renal function but is not the priority given these symptoms.
Digoxin Toxicity
Toxic effect of digoxin causing GI, visual, and cardiac symptoms, worsened by hypokalemia.
- Therapeutic digoxin level: 0.5–2.0 ng/mL
- Classic signs: nausea, vomiting, visual halos, bradycardia
- Hypokalemia increases risk of toxicity
Memory trick: 'Low K, high risk' — low potassium raises digoxin danger.