<prompt> Carcinoid tumor is diagnosed by.Urinary 5 HIAAChromogranin ANeuron specific enolaseUrinary 5 Hydroxy tryphtophan  <response>: Ans. a Urinary 5HIAARef: Bailey 27th edition, Page 1251 Most common used investigation to diagnose carcinoid tumor is 24 hours urinary 5HIAA IOC to localize the tumor is DOTATATE scan 