This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thyroid Malignancies, Subject name: Surgery
Which of the following is true about medullary CA of thyroid - 
Select and explain. 
A. Associated with MET oncogene, B. Elavated levels of Serum calcitonin, C. Seen in MEN I syndrome, D. Most common thyroid cancer
B: Elavated levels of Serum calcitonin
Answer: B: Elavated levels of Serum calcitonin 
Explanation: Ans. is 'b' i.e., Elavated levels of Serum calcitonin o In Medullary carcinoma serum calcitonin is increased, whose function is to lower serum calcium levels. So hypocalcemia may be found associated with MTC.# Seen in MEN IIA and B# Associated with RET Protooncogeneo MTC secrets not only calcitonin but also some other peptides such as :# CEA# CGRP (Calcitonin gene-related peptide)# Histaminadases# Prostaglandin E2 and F2# Serotonin# ACTH (may lead to cushing syndrome in about 2 to 4% of pts.)