system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 58-year-old woman comes to the physician for evaluation of worsening fatigue for 1 week. She also has a 1-year history of hand pain and stiffness. Four months ago, she started a new medication for these symptoms. Medications used prior to that included ibuprofen, prednisone, and hydroxychloroquine. Examination shows a subcutaneous nodule on her left elbow and old joint destruction with Boutonniere deformity. Her hemoglobin concentration is 10.1 g/dL, leukocyte count is 3400/mm3, and platelet count is 101,000/mm3. Methylmalonic acid levels are normal. Which of the following could have prevented this patient's laboratory abnormalities?
assistant
Leucovorin