This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrine, Subject name: Pathology
Medullary ca of thyroid is associated with increase in 
Select and explain. 
A. Calcitonin, B. Thyroglobulin, C. T3, D. T4
A: Calcitonin
Answer: A: Calcitonin 
Explanation: Ans. (a) Calcitonin(Ref: Robbins 9th/pg 1099-1100)*In Medullary Carcinoma Thyroid, serum Calcitonin is elevated.*Elevated serum calcitonin also provides a marker of residual or recurrent disease.*All patients with Medullary Carcinoma Thyroid*should also be tested for RET mutations, so that genetic counseling and testing of family members can be offered;