This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epilepsy, Subject name: Pharmacology
[{'content': 'A patient on phenytoin therapy develops depression, for which he was prescribed tricyclic anti-depressants. He now complains of lassitude and his Hb reading is 8 gm/dl, the next step in the management of this patient is: \nSelect and explain. \nA. Chest X ray, B. MCV should be estimated, C. GGT should be estimated, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (B) MCV should be estimated(Ref: KD T 8/e p441)Phenytoin can induce folate deficient megaloblastic anemia that can be diagnozed by measuring MCV.', 'role': 'assistant'}]