This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Drugs & Other Biological Methods of Treatment, Subject name: Psychiatry
HIAA is a metabolite of: 
Select and explain. 
A. Serotonin, B. Dopamine, C. Epinophrine, D. Histamine
A: Serotonin
Answer: A: Serotonin 
Explanation: Ans is 'a' i.e. SerotoninSerotonin or 5 hydroxytryptamine is catabolized to 5 Hydroxy indole acetic acid (5HIAA).The enzyme which catalyzes this reaction is - Monoamine oxidase.5 HIAA is excreted normally in urine. Normal adult excretes about 7 mg of HIAA per day.