Your client has been prescribed warfarin for the prevention of blood clots due to atrial fibrillation. Which statement by the client shows that the client understands their medication.

A. "If I miss a dose of hy medication I can just double up the next day.": Doubling the dose of an anticoagulant like warfarin significantly increases the risk of life-threatening hemorrhage. Because warfarin has a narrow therapeutic index and a long half-life, sudden changes in dosing lead to unpredictable fluctuations in the INR. Patients should be instructed to take the missed dose as soon as remembered or skip it entirely as directed. B. "I will eat broccoli and collard greens three times a week and I can have extra helpings to improve my iron intake.": Broccoli and collard greens are extremely rich in Vitamin K, which functions as the direct physiological antagonist to warfarin. Increasing the intake of these vegetables will lower the INR and render the anticoagulant therapy ineffective, increasing the risk of stroke. Patients must maintain a consistent, stable intake of Vitamin K rather than increasing it. C. "I will need to get frequent blood work to check the INR level, that shows if this medication is at the right dose.": The International Normalized Ratio (INR) is the standardized laboratory measurement used to monitor the effectiveness of warfarin therapy. Regular testing is essential to ensure the patient remains within the target therapeutic range, usually between 2 and 3 for atrial fibrillation. This statement confirms the patient understands the necessity of ongoing clinical monitoring for safety. D. "I should eat 1-2 bananas a day because this medication can cause me to loose potassium through my urine.": Warfarin does not affect renal tubular function or cause the excretion of electrolytes like potassium. This instruction is relevant for patients taking loop or thiazide diuretics, but it has no pharmacological basis for those on anticoagulant therapy. This statement indicates a confusion between the side effects of diuretics and those of vitamin K antagonists.