Causes, Symptoms and Treatment of Carcinoid Syndrome

The main characteristics of carcinoid syndrome are flushing, hot flashes, tachycardia, and diarrhea. Today's article will explain why it happens and how the field of oncology treats it.
Causes, Symptoms and Treatment of Carcinoid Syndrome

Last update: 16 March, 2021

Carcinoid syndrome refers to a set of signs and symptoms that are a complication of carcinoid tumors. These often secrete chemicals such as serotonin.

This isn’t the most common type of cancer. In fact, these tumors and carcinoid syndrome are quite aggressive. Also, many people with it experience shortness of breath and even tachycardia.

Today’s article will describe everything you need to know about the disorder and how doctors treat it.

What is carcinoid syndrome?

This syndrome is basically a set of signs and symptoms that are due to the action of certain substances released by a tumor. According to an article published in the Revista Médica de Costa Rica y Centroamerica, most carcinoid tumors develop from neuroendocrine cells of the gastrointestinal tract.

In fact, estimates indicate that about 50% of all small bowel cancers are of this type. However, they can also appear in the lung, pancreas, and liver. The truth is carcinoid syndrome only affects about 8% of those afflicted by these tumors.

It’s actually more frequent in those with extensive metastases in the liver. The tumor releases substances such as serotonin, histamine, and prostaglandins, and all of these can impact many parts of the body and lead the characteristic symptoms.

Symptoms of carcinoid syndrome

According to Mayo Clinic specialists, one of the most common symptoms is redness of the skin. It usually affects the face and upper chest. This is because many of the chemicals mentioned cause vasodilation.

The redness appears abruptly and lasts from minutes to hours. It’s sometimes triggered by certain agents that also produce vasodilatation, such as exercise or alcohol. There’s also hypotension, dizziness, and fatigue.

Diarrhea is another common symptom, especially when the tumor releases serotonin. This is because it acts on intestinal motility. Thus, stools are usually watery and there may be abdominal cramps.

Carcinoid syndrome also manifests with tachycardia and shortness of breath. It’s similar to an anxiety attack. Some people have decreased sex drive, heart murmurs, and added breath sounds.

A woman with a belly ache.
Diarrhea due to carcinoid syndrome is due to the excessive release of serotonin that impacts intestinal motility.

Possible complications

Carcinoid syndrome can lead to numerous complications. According to a study published in the Revista Chilena de Cardiología, one of the most relevant is carcinoid heart disease. It happens because plaques of fibrous tissue form on the heart valves.

Specifically, the most affected areas are the right heart valves (tricuspid and pulmonary). In fact, this leads to heart failure later on.

Carcinoid crises are another complication. This happens when the syndrome aggravates due to a trigger that intensifies the symptoms. When using anesthetics for surgery, for example. Blood pressure can drop way low and lead to a life-threatening shock.

Intestinal obstruction is also among the complications of carcinoid syndrome. However, it tends to be a consequence of the tumor itself. The bowel loops can twist when it reaches a significant size or spreads to the nodes.

What causes carcinoid syndrome?

The signs and symptoms that characterize carcinoid syndrome as such derive from the chemicals a tumor produces. We already mentioned them above, they’re serotonin, histamine, prostaglandins.

The explanation as to why the carcinoid syndrome doesn’t occur in all tumors is that the liver usually neutralizes these chemical agents before they produce their action. However, the organ is damaged in those who have many liver metastases.

Risk factors for liver metastasis

The main risk factor for carcinoid syndrome is clearly having a carcinoid tumor. At the same time, certain circumstances can increase the probability of experiencing this type of cancer.

The main indicator is having a family history of the same type of tumor. Also if there are cases of multiple endocrine neoplasia 1 or neurofibromatosis type 1 in the family.

As carcinoid tumors usually develop in the digestive tract, it’s important to mention the things that promote their appearance. Pernicious anemia or atrophic gastritis are among them.


The diagnosis for carcinoid syndrome is usually through symptoms. The patient needs to explain all details to the attending physician. Also, they may already know the existence of an underlying tumor.

However, carcinoid syndrome is the first manifestation of cancer in some cases. It’s, therefore, important to conduct a series of complementary tests to confirm it. Blood and urine tests are useful. This is because they make it possible to see if any substance is above its usual concentration.

Magnetic resonance imaging and computed tomography analyze the existence of a tumor and its location. There are others, such as PET-CT, which help locate metastases.

Treatment of carcinoid syndrome

A person undergoing an MRI.
Imaging studies can locate the tumor that causes the syndrome.

To address carcinoid syndrome, it’s essential to treat any underlying cancer. A study published in Endocrinología y Nutrición explains the types of therapeutics currently available. They vary according to the characteristics of the tumor and, above all, the presence of metastases.

Surgery is one option to try to remove part of the tumor or all of it. Also, they often use biological drugs, such as interferon-alpha. This is because these stimulate the immune system that challenges cancer.

They may also use the embolization of the hepatic artery if there are metastases in the liver. In this way, they cut off the main blood flow to the organ and the tumor can no longer grow. Chemotherapy may also be helpful as can radiofrequency ablation.

Additionally, there are numerous medications one can use to relieve the symptoms of carcinoid syndrome as such. For example, octreotide and lanreotide are analogs of a substance important to the digestive system called somatostatin. In fact, they can reduce diarrhea and flushing.

Carcinoid syndrome is derived from a tumor

It’s important to re-emphasize that carcinoid syndrome is due to the action of substances generated by a carcinoid tumor. These tumors develop in the gastrointestinal tract in most cases. However, they can also appear in the lung or metastasize to the liver.

It’s essential to be able to recognize the symptoms of this syndrome, such as hot flushes, shortness of breath, and tachycardia. Finally, it’s always necessary to rule out symptoms that have to do with a neoplasm when they appear.

If you have any questions, make sure to talk to your doctor. 

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