Carcinoid syndrome is a group of symptoms associated with carcinoid tumor (see bronchial adenoma ). Carcinoid tumors occur most commonly in the gastrointestinal tract, including the stomach, small intestine, appendix, colon and rectum, or in the lungs. In rare circumstances, carcinoid tumors can develop in the ovaries. Carcinoid tumors secrete excessive amounts of the hormone serotonin as well as other chemicals that cause the blood vessels to dilate (open). These tumors may also cause diarrhea and wheezing (asthma). Carcinoid tumours may be found as an incidental finding in up to 10% of post-mortem examinations.
Carcinoids may occur in multiple sites , and, except for those of rectal origin, may produce an endocrine substance called serotonin. There are wide variations in the chemicals secreted by these tumors, and the symptoms depend on the mix of chemicals made by the particular tumor.Normally, an amino acid called tryptophan is used by the body to make niacin and certain proteins, but in carcinoid syndrome, it forms serotonin instead. Most serotonin is changed by the body to 5-hydroxy indole acetic acid.The most bothersome symptoms include bright red facial flushing, diarrhea and occasionally wheezing.
A specific type of heart valve damage may occur, as well as other cardiac problems. Carcinoid tumours are associated with MEN (multiple endocrine neoplasia) type 1 in about 10% of cases. Treatment of carcinoids syndrome depand on the size of the tumor. Surgical resection when possible is the treatment of choice. Surgery should be considered for patients with liver metastases and potentially resectable disease. Drugs that block the action of serotonin and/or histamine may be successful in relieving the symptoms. Diarrhea and abdominal cramping may be treated with hydration and diphenoxylate with atropine (Lomotil).
Octreotide (a somatostatin agonist) may also be helpful. Increased protein and a low-fat diet are often recommended. Multivitamin mineral and low-dose nicotinic acid (niacin) supplements may be prescribed. Other items sometimes recommended are fish oil capsules, electrolyte supplements, and in some cases, large portions of nutmeg. Patients are advised to ingestion of alcohol, large meals, and foods high in tyramine, as these may provoke symptoms. Sandostatin (octreotide) injections are given to those with advanced carcinoid tumors that cannot be removed surgically.
