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Carcinoid Syndrome (cont.)

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What are the symptoms of carcinoid syndrome?

Typical carcinoid symptoms include:

  • flushing
  • diarrhea
  • abdominal pain
  • and wheezing due to bronchospasm (airway narrowing)
  • valvular heart disease
  • surgery can provoke a complication known as carcinoid crisis.


  • Flushing is the most common symptom of carcinoid syndrome. An estimated 90% of the patients have flushing some time during their illness.
  • Flushing is characterized by redness or purple discoloration of the face and neck (or upper body) accompanied by a warm sensation.
  • Episodes of flushing typically occur suddenly, either spontaneously or brought on by emotional stress, physical stress, or drinking alcohol.
  • Episodes of flushing can last minutes to hours. Flushing can be accompanied by palpitations, low blood pressure, or fainting if blood pressure becomes too low to supply blood to the brain. Rarely, flushing can be accompanied by high blood pressure.
  • Substances responsible for flushing have not been clearly identified; possible candidates include serotonin, bradykinin, and substance P.


  • Diarrhea is the second most common symptom of carcinoid syndrome. An estimated 75% of patients with carcinoid syndrome have diarrhea.
  • Diarrhea often occurs with flushing, but also can occur alone.
  • Diarrhea in carcinoid syndrome is most likely caused by the hormone serotonin. Medications that block the action of serotonin such as ondansetron (Zofran) often alleviate the diarrhea.
  • Sometimes diarrhea in the carcinoid syndrome can be due to a local effect of the tumor partially obstructing the small intestine.

Heart disease

Heart disease occurs in an estimated 50% of patients with the carcinoid syndrome. Carcinoid syndrome typically causes scarring and stiffness of the tricuspid and pulmonic valves of the right side of the heart. Stiffness of these two valves decreases the ability of the heart to pump blood from the right ventricle to the lungs and to the rest of the body and leads to heart failure.

Typical symptoms of heart failure include an

  • enlarged liver (due to the backup of blood returning to the failing heart which is unable to pump all of the blood returning to it),
  • swelling of the feet and ankles (edema), and
  • swelling of the abdomen due to fluid accumulation (ascites).

The damage to the tricuspid and pulmonic valves of the heart in the carcinoid syndrome is most likely caused by prolonged exposure to high levels of serotonin in the blood.

Carcinoid crisis

Carcinoid crisis is a dangerous condition that can occur at the time of surgery. It is characterized by a sudden and profound drop in blood pressure causing shock, sometimes accompanied by an abnormally fast heart rate, high blood glucose, and severe bronchospasm. Carcinoid crisis can be fatal. The best way to prevent carcinoid crisis is to treat patients undergoing surgery with somatostatin (see below) before surgery begins.


Wheezing occurs in approximately 10% of the patients with carcinoid syndrome. It is the result of bronchospasm (constriction of the bronchial airways) caused by hormones released by the carcinoid tumors.

Abdominal pain

Abdominal pain is common in patients with carcinoid syndrome. The pain may be due to tumor metastases in the liver, tumor invading neighboring tissues and organs, or tumor causing bowel obstruction (please see small bowel carcinoid tumors below).

Medically Reviewed by a Doctor on 8/22/2016


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