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: Pathology
[{'content': 'Medullary ca of thyroid is associated with increase in- \nSelect and explain. \nA. Calcitonin, B. Thyroglobulin, C. T3, D. T4', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Medullary carcinomas of thyroid are neuroendocrine tumours derived from the parafollicular cells or C cells. They secrete calcitonin,the measurement of which plays an impoant role in the diagnosis and post operative follow - up of patients.Calcitonin is readily demonstrable within the cytoplasm of tumour cells as well as in stromal amyloid by immunohistochemical methods. Ref: Robbins and cotrans 9e Pg 1099', 'role': 'assistant'}]