ROSH Geriatrics Practice Test

Carcinoid tumors, which are neuroendocrine tumors often arising in the gastrointestinal tract, can lead to a variety of symptoms due to the hormones they produce. One of the hallmark symptoms associated with these tumors is diarrhea. This occurs because carcinoid tumors can release serotonin and other vasoactive substances into the bloodstream, resulting in increased gastrointestinal motility. The excess serotonin often leads to flushing, wheezing, and the characteristic diarrhea seen in patients with carcinoid syndrome. This syndrome typically occurs when the tumor secretes enough serotonin to enter systemic circulation, bypassing the liver's first-pass metabolism, which would normally metabolize much of it. Therefore, understanding the pathophysiological basis behind the secretion of serotonin by carcinoid tumors provides insight into their clinical presentation, particularly the diarrhea that is frequently noted as a significant symptom.