This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pediatrics
[{'content': 'Nelson syndrome is seen in: \nSelect and explain. \nA. Adrenalectomy, B. Hypopitutarism, C. Deficiency of beta cells, D. Deficiency of growth hormone', 'role': 'user'}, {'content': "Answer: A \nExplanation: a. Adrenalectomy(Ref: Nelson's 20/e p 2714-2723, Ghai 8/e p 526-527)Adrenalectomy, in a case of pituitary adenoma, may lead to increased ACTH secretion by an unresected pituitary adenoma, evidenced mainly by marked hyperpigmentation; this condition is termed Nelson syndrome.", 'role': 'assistant'}]