Carcinoid Syndrome Definition

Carcinoid syndrome is a complex of different symptoms that occur together. The cause of the disease is usually tumors. Their development is related to so-called neuroendocrine systems. The focus is on a tumor that produces the messenger substance serotonin and is itself of a neuroendocrine type. In many cases, the carcinoid syndrome causes symptoms only in the late stages, so that the diagnosis of the disease is often delayed for a long time.

What is carcinoid syndrome?

The hallmark symptoms of the disease include paroxysmal diarrhea accompanied by abdominal cramps and watery stools.

As part of the carcinoid syndrome, a neuroendocrine tumor triggers various symptoms in the affected patients. For example, the main symptoms of carcinoid syndrome include diarrhea, pain in the abdominal area, sudden reddening of the skin, and difficulty breathing. The cardiovascular system may also be affected by the disease. The carcinoids appear in the form of neoplasms that are epithelial and neuroendocrine in nature. See AbbreviationFinder for abbreviations related to Carcinoid Syndrome.

They also have hormone activity. They produce various substances, such as serotonin, kallikrein or histamine. The name of the disease derives from the corresponding tumor. Its discovery in 1907 goes back to Oberndorfer. In principle, it is possible for the tumor to affect all types of neuroendocrine tissue. In the majority of cases, however, the tumor forms in the lungs, colon, stomach or appendix.

The tumors differ from others in their external appearance and coloration. They may develop in people who have hypergastrinemia. This is a condition in which the substance gastrin is secreted into the blood in excess. This is the case, for example, in the context of the so-called Zollinger-Ellison syndrome.


The cause of the development of the carcinoid syndrome is primarily due to the excessive release of the neurological messenger substance serotonin. Certain neuroendocrine cells are responsible for this release. There is a degeneration of these cells. In this way, the function of the liver is changed.

The cells of the liver contain the so-called monoamine oxidase, which acts as a catalyst for the decomposition of serotonin from the tumor. The serotonin is converted into the substance 5-hydroxyindolacetoacetic acid, which no longer has any biological activity. For this reason, the concentration of the substance in the patient’s urine can be used to make the diagnosis.

Symptoms, Ailments & Signs

The spectrum of possible symptoms of carcinoid syndrome is relatively wide. The hallmark symptoms of the disease include paroxysmal diarrhea accompanied by abdominal cramps and watery stools. During these phases, the face often turns reddish to violet. Similar discoloration of the skin may also appear on the legs or neck.

If the carcinoid syndrome remains untreated, various complications are the result in some cases. For example, defects in the heart valves, a lack of vitamin B2 and so-called telangiectasia are possible. In the majority of cases, the tumors develop in the area of ​​the gastrointestinal tract.

The appendix and the ileum are particularly frequently affected by the carcinoids. In addition, an occurrence in the lungs is also possible. When the tumors metastasize, they usually do so in the liver. The typical symptoms arise primarily because the concentration of vasoactive substances in the organism suddenly increases.

The so-called flush manifests itself in symptoms such as increased sweat production, tachycardia and reddened skin. In addition, some patients complain of hot flashes. The diarrhea is also caused by the corresponding substances. However, the majority of the symptoms only appear when the tumors have already formed metastases in the liver . For this reason, the diagnosis is often made relatively late.

Diagnosis & course of disease

A large proportion of patients only show typical symptoms of carcinoid syndrome when the tumors have metastasized in the liver. Thus, the disease is often diagnosed at a late stage. If carcinoid syndrome is suspected, a specialist should be consulted, who will discuss the symptoms with the patient and find out about their lifestyle and any chronic diseases.

Finally, through the use of various examination methods, important information about the present disease is collected. An analysis of the urine is primarily used to determine the concentration of the substance 5-HIAA. If the threshold values ​​are exceeded, the carcinoid syndrome can be diagnosed with relative certainty.

In addition, imaging methods and examinations of tissue samples are used. The differential diagnosis plays an important role, in which, for example, enzyme defects in connection with serotonin or histamine have to be clarified. An intolerance to the substance histamine or migraine attacks are possible here.


Carcinoid syndrome causes the sufferer to suffer from various tumors that can be located anywhere in the body. This leads to the usual symptoms and complications of cancer, which can also significantly reduce the life expectancy of those affected. In many cases, carcinoid syndrome is diagnosed late, leading to irreversible sequelae and premature death of the patient.

Malformations and defects in the heart occur, which can lead to cardiac death. Carcinoid syndrome also often leads to discoloration of the skin or face. Patients suffer from severe diarrhea and abdominal pain. Hot flashes or sweating also occur. Those affected also suffer from tachycardia and may lose consciousness. The quality of life is significantly restricted by the carcinoid syndrome.

Treatment of carcinoid syndrome, as a rule, does not lead to special complications. However, there is not always a positive course of the disease. The tumors are surgically removed. The affected person is dependent on taking various medications and on regular check-ups to prevent further tumors from developing.

When should you go to the doctor?

If you notice gastrointestinal discomfort, an unusual discoloration of your face, and other typical symptoms of carcinoid syndrome, you should see your doctor. Sudden sweating, tachycardia or reddened skin are also warning signs that need to be clarified quickly. Deficiency symptoms and signs of cardiac arrhythmia indicate that the disease is already more advanced. At this point at the latest, a doctor should be consulted who can clarify the symptoms and complaints and, if necessary, initiate treatment.

Since the disease is usually only discovered in the late stages, treatment must be started immediately. During treatment, close consultation with the doctor responsible should be maintained. In the case of unusual symptoms or side effects and interactions, the patient must inform the doctor, otherwise serious complications can arise. The right contact person is the general practitioner or an internist. Patients in whom the syndrome occurs as part of another illness are best advised to speak to their doctor. Children should be presented to a pediatrician immediately.

Treatment & Therapy

Treatment of carcinoid syndrome should begin immediately after diagnosis, as the disease is usually discovered late. The treatment of choice is removal of the primary tumor, which is performed as part of a surgical procedure. Metastases must also be removed. Another possibility is the administration of active ingredients that slow down the growth of the tumors.

Outlook & Forecast

The prognosis for carcinoid syndrome depends on various factors. In the early stages of the disease and in good general health, a cure is quite possible. If the patient follows the doctor’s instructions and medical measures are initiated immediately, there is a chance of recovery. Nevertheless, the tumors must be surgically removed and cancer therapy must be used. Both are associated with numerous side effects and risks. Complications can occur that worsen the prognosis.

In most cases, in the case of a carcinoid syndrome, several tumors have already formed in different places in the organism. They pose a potential threat to the life of the patient. If the body is already severely weakened due to a previous illness and a large number of cancer cells have formed, the prospect of recovery dwindles. In addition, the disease is often only noticed at an advanced stage of development. This complicates treatment and reduces the prospect of health improvement.

If the growth of the tumors cannot be contained and ultimately prevented completely, the patient dies prematurely. If metastases form, the prognosis worsens. In the final phase of the disease, doctors are mainly concerned with relieving the unpleasant symptoms.


There are currently no known measures to prevent carcinoid syndrome.


In most cases, the patient with carcinoid syndrome has very few or no follow-up measures available, so that the patient with this disease is primarily dependent on a quick and, above all, early diagnosis. It cannot heal itself and early detection of the disease usually always has a very positive effect on the further course.

In carcinoid syndrome, the tumor usually has to be removed. The further course depends heavily on the type and severity of the tumor, so that a general prediction is not possible here. However, the person affected should definitely rest after the procedure and take care of their body. Physical exertion or stressful activities should be avoided.

The support of one’s own family or friends is also very important in the case of carcinoid syndrome, whereby loving and intensive discussions are also necessary so that no psychological problems or depression can occur. In many cases, however, carcinoid syndrome significantly reduces the life expectancy of those affected because the syndrome is not recognized until late.

You can do that yourself

In most cases of carcinoid syndrome, there are no options for self-help. When diagnosing the syndrome, those affected rely on further tests to identify the primary disease or tumor.

In addition to the physical symptoms, many of those affected also suffer from mental illnesses or depression. It is advisable to talk to those closest to you and your family about the disease and how it will progress. Children in particular should be informed about the disease, and the possible negative consequences should also be mentioned. Conversations with other sufferers who can report helpful information often help. However , psychological treatment can also be useful for the patient’s relatives, partner or parents.

Those affected should take it easy on themselves if they have carcinoid syndrome and not put unnecessary strain on their bodies. Sporting activities should also generally be avoided. After the tumors have been removed, patients are dependent on regular examinations to prevent the disease from recurring.

Carcinoid Syndrome