<prompt> Increased level of 5 HIAA is seen in which disease:Carcinoid tumorPhenylketonuriaPheochromocytomaGastrinoma  <response>: Ans. a Carcinoid tumorRef: Bailey and Love 27th edition, Page 1251Sabiston 20th edition, Page 1273Diagnosis of carcinoid tumors NET: NET produce serotonin in enormous amount -- which is then metabolized in lungs and liver to inactive product known as 5-hydroxyindoleaceticacid. Increased urinary levels of 5-HIAA in 24 hours urinary samples is used to diagnose Carcinoid tumor. It is more specific to diagnose. Sensitivity is low. A combination of 5HIAA and Chromogranin A is used to diagnose the tumor with increased sensitivity and specificity Chromogranin A is better than 5 HIAA in diagnosis as alone. Now a new combination of Chromogranin A N-terminal pro brain natriuretic peptide NT-pro BNP to diagnose as well as to show the worse survival of the patients. 