Cases of small intestine neuroendocrine tumor can be diagnosed by urine sampling.
A large fraction of cases are diagnosed after routine surgery for bowel obstruction. Others may be diagnosed incidentally, or after investigation for carcinoid syndrome. The tumor typically produces serotonin, Tachykinin peptides and other substances, which cause flushing, tachycardia, diarrhea and in some cases fibrosis of the heart valves. 
