Carcinoid syndrome


  • Carcinoid tumors are neuroendocrine malignancies
  • Primary tumors can be located in:[1]
    • Gastrointestinal tract (55%)
    • Bronchopulmonary system (30%)
    • Other sites rarer or may actually be metastases (ovary, liver, gallbladder, thymus, middle ear)
  • Syndrome results from tumor production of serotonin, histamine, bradykinin, kallikrein, and/or prostaglandin

Clinical Features

  • Vasodilation
    • Due to increased histamine and kinin production
    • Cutaneous flushing
    • Hypotension, vasodilatory shock
  • Diarrhea
  • Bronchospasm
  • Cardiac valvular lesions
    • Due to serotonin-stimulated fibroblast growth/fibrogenesis
    • Can cause tricuspid or pulmonary regurgitation or stenosis, right heart failure more common than left

Differential Diagnosis

Acute allergic reaction

Oncologic Emergencies


  • Evaluation to rule out other causes of shock, diarrhea, etc.
  • 24 hour urinary HIAA (5-hydroxyindoleacetic acid)
  • Echocardiography
  • Imaging to locate the tumor, if not known


See Also


  1. Strosberg, JR. Clinical charecteristis of carcinoid tumors. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on August 20, 2016.)
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