Carcinoid syndrome

Carcinoid syndrome commonly presents with flushing and diarrhea. Other clinical features include wheeze, palpitations, telangiectasia, and abdominal pain.

Symptoms develop due to secretion of serotonin, kinins, and other biogenic amines from functional secretory neuroendocrine tumors.

Diagnosed by elevated levels of urinary 5-hydroxyindoleacetic acid. Chromogranin A is often elevated in the presence of liver metastases.

Treatments include medical therapies (somatostatin analogs, radionuclide therapies) and surgical options (resection of primary and secondary tumors).

Complications include carcinoid heart disease and carcinoid crisis at times of stress (e.g., during surgery).

Carcinoid syndrome occurs due to release of serotonin (5-hydroxytryptamine) and other vasoactive peptides into the systemic circulation from a carcinoid tumor. A total of 20% to 30% of midgut neuroendocrine tumors (NETs), 5% of bronchial carcinoid tumors, and approximately 1% of pancreatic NETs secrete 5-hydroxytryptamine and other peptides. In patients with these tumors, carcinoid syndrome develops. The principal features of carcinoid syndrome are diarrhea and flushing. Wheezing, telangiectasia, and abdominal pain can also occur.