Carcinoid syndrome diarrhea
Diarrhea is often the revealing symptom in patients suffering from carcinoid syndrome secondary to a carcinoid tumor. The etiology of this burdensome diarrhea is thought to be hypersecretion of serotonin from neuroendocrine cells. Diagnosis is made based on clinical symptoms and two biomarkers, 5-hydroxyindoleacetic acid (found in the urine) and chromogranin A (found in the serum). Synthetic somatostatin analogues (SSAs) have been a staple of therapy for years and continue to be used. Telotristat is the first oral medication indicated in combination with SSAs for patients with carcinoid syndrome diarrhea who no longer respond to SSAs alone.
Jacobs, Brennan; Lee, Sangkuk; and Goldwire, Micheline A., "Carcinoid syndrome diarrhea" (2017). Regis University Faculty Publications (comprehensive list). 373.