Carcinoid crisis and other complications from carcinoid syndrome
Complications of carcinoid syndrome may arise due to the abnormally high levels of substances produced by a functional neuroendocrine tumor. These complications can include carcinoid crisis, pellagra, the formation of scar tissue in the mesentery (also called mesenteric fibrosis), and carcinoid heart disease.
Carcinoid crisis is a potentially life-threatening complication of carcinoid syndrome caused by the sudden release of high levels of serotonin and other active substances from a NET.1,2 This sudden release of active substances may be caused by tumor manipulation during surgery, needle biopsy of the tumor, or the administration of anesthesia agents.1,2
To protect against a carcinoid crisis during surgery, a patient should be treated with a somatostatin analog, such as Octreotide, either before and/or during the procedure.1,2,3 Octreotide is usually administered by intravenous infusion if the procedure is prolonged.
Protecting yourself from carcinoid crisis
Some health care providers may not be aware of the threat of a carcinoid crisis and how to protect against it. Therefore, it is important to talk to all health care providers about a carcinoid syndrome diagnosis to educate them about the risk of carcinoid crisis.
Pellagra is characterized by diarrhea, skin rash, memory problems, or confusion.2,5 The result of niacin deficiency (vitamin B3), roughly 5% of those with carcinoid syndrome, experience this complication.4 Pellagra is thought to occur as an indirect result of abnormally high levels of serotonin being produced by the body. Because most of the amino acid tryptophan (required by the body to make both vitamin B3 and serotonin) is used to make serotonin, a deficiency of vitamin B3 occurs that leads to pellagra.5
Formation of scar tissue in the mesentery (also called Mesenteric Fibrosis)
The mesentery is a fold of tissue (membranes) that connects the intestine to the abdominal wall and holds the intestine in place. Scar tissue may form in the mesentery of patients with carcinoid syndrome, and this scar tissue may cause problems in the intestine. These problems can include blockage of blood flow to the intestine and/or intestinal obstruction, which can decrease or prevent the flow of food from passing through the gut. 1,2,5 Symptoms of bowel obstruction include abdominal pain, loss of appetite, constipation, vomiting, and the inability to have a bowel movement or pass gas. 6 Bowel obstruction is a serious condition that can be life-threatening, and people experiencing symptoms should seek help immediately. 6
Carcinoid heart disease (CHD)
Carcinoid heart disease is the collective term used to describe all heart problems associated with people who have carcinoid syndrome.7 It occurs when large amounts of active substances (e.g., serotonin, tachykinins) reach and cause damage to the right side of the heart. As a result, people with carcinoid syndrome may develop tissue scaring (also called fibrosis) most commonly on the right side of the heart and experience complications associated with cardiac disease. The left side of the heart is often undamaged because the lungs break down (metabolize) the active substances before they reach the left side of the heart.
1 Gade A, Olariu E, Douthit N. 2020. “Carcinoid syndrome: A review.” Cureus 12 (3): e7186.
2 Pandit S, Annamaraju P, Bhusal K. 2020. Carcinoid Syndrome. Internet: StatPearls. Accessed August 13, 2020. https://www.ncbi.nlm.nih.gov/books/NBK448096.
3 Vinik A, Woltering E, O’Dorisio T, et al. 2015. “Evaluation and management of neuroendocrine tumors.” Chap. 7 in Neuroendocrine Tumors: A comprehensive guide to diagnosis and management, 215.
4 Loughrey PB, Zhang D, Heaney AP. 2018. “New treatments for the carcinoid syndrome.” Endocrinol Metab Clin N Am 47: 557-576.
5 Ferrari A, Glasberg J, Riechelmann R. 2018. “Carcinoid syndrome: update on the pathophysiology and treatment.” Clinics (73) (supp 1): e490s.
6 Mayo Clinic. n.d. Intestinal Obstruction. Accessed August 24, 2020. https://www.mayoclinic.org/diseases-conditions/intestinal-obstruction/symptoms-causes/syc-20351460.
7 Ram P, Penalaver J, Lo K, et al. 2019. “Carcinoid heart disease: Review of current knowledge.” Tex Heart I J 46 (1): 21-27.