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: Medicine
Which of the following is most likely to be raised in patients with Atypical carcinoids 
Select and explain. 
A. 5 HIAA, B. 5 HTP, C. VMA, D. Metanephrines
B: 5 HTP
Answer: B: 5 HTP 
Explanation: Answer is B (5 HTP): Elevated levels of urinary 5 HTP is suggestive of an atypical carcinoid syndrome Note that patients with atypical carcinoid syndrome may have elevated levels of 5HT, 5HTP and 5HIAA, but the presence of increased urinary 5HTP is most typical feature to suggest on Atypical carcinoid