Carcinoid syndrome

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  • 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

Related to Local Tumor Effects

Related to Biochemical Derangement

Related to Hematologic Derangement

Related to Therapy


  • 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

External Links


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