This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Carcinoid syndrome is due to: March 2013 
Select and explain. 
A. Adrenaline, B. Noradrenaline, C. Serotonin, D. Dopamine
C: Serotonin
Answer: C: Serotonin 
Explanation: Ans. C i.e. Serotonin Carcinoid syndrome It refers to the array of symptoms that occur secondary to carcinoid tumors. The syndrome includes flushing and diarrhea, and, less frequently,hea failure and bronchoconstriction. It is caused by endogenous secretion of mainly serotonin and kallikrein.