The nurse is preparing to administer digoxin (Lanoxin) to a client experiencing atrial fibrillation. Which of the following electrolyte imbalances would the nurse assess to reduce the incidence of toxicity with digoxin (Lanoxin)?

A) Hypokalemia: Hypokalemia, or low potassium levels, significantly increases the risk of digoxin toxicity. Since digoxin competes with potassium for binding at the sodium-potassium ATPase site in the heart, low potassium levels can lead to increased digoxin effects and toxicity. Therefore, it is crucial to monitor potassium levels and correct any deficiencies before administering digoxin. B) Hyperkalemia: While hyperkalemia is a serious concern and can also affect digoxin therapy, it usually results in decreased effectiveness of digoxin rather than increasing toxicity. Elevated potassium levels can diminish the drug's positive inotropic effect. C) Hypocalcemia: Although calcium levels can influence cardiac function, hypocalcemia is not directly related to digoxin toxicity. Monitoring calcium is important for overall cardiac health, but it is not the primary focus when assessing the risk for digoxin toxicity. D) Hypernatremia: Elevated sodium levels do not have a direct impact on the efficacy or toxicity of digoxin. While sodium levels are essential to monitor for overall health, they are not critical in the context of digoxin administration and toxicity risk.