Carcinoid Syndrome – Symptoms and Causes
Overview
Carcinoid syndrome occurs when a specific type of tumor releases chemicals like serotonin into the bloodstream. These carcinoid tumors typically develop in the digestive tract, including the stomach, small intestine, appendix, colon, and rectum.
Only a small number of carcinoid tumors release the chemicals that trigger symptoms.
Most people with carcinoid syndrome have cancer that has already spread to the liver, which compromises the body’s ability to filter these harmful chemicals. Scientists haven’t yet determined exactly what causes carcinoid tumors to form in the first place.
Signs and Symptoms
Carcinoid syndrome happens when a rare cancerous tumor called a carcinoid tumor releases certain chemicals into your bloodstream. These chemicals can cause several noticeable symptoms.
The most common symptoms include:
- Facial flushing: Your face and sometimes neck may turn red and feel warm.
- Diarrhea: Often watery and frequent.
- Wheezing: Difficulty breathing similar to asthma.
- Fast Heartbeat: Your heart may race or beat irregularly.
Other symptoms you might experience:
- Abdominal pain
- Weight loss without trying
- Weakness or fatigue
- Skin lesions on the face
Symptoms often come in “attacks” that may last minutes to hours. These attacks can be triggered by:
| Trigger | Examples |
|---|---|
| Foods | Alcohol, spicy foods |
| Emotional states | Stress, anxiety |
| Physical activity | Exercise, heavy lifting |
| Medical procedures | Surgery, anesthesia |
When to Call a Healthcare Provider
Contact your doctor if you notice:
- Persistent flushing that doesn’t go away.
- Unexplained diarrhea that lasts more than a few days.
- Wheezing or trouble breathing with no known cause.
- Heart palpitations or an irregular heartbeat.
Seek emergency care if you experience severe shortness of breath or fainting episodes, as these may indicate a carcinoid crisis, which requires immediate medical attention.
Causes
Carcinoid syndrome happens when rare tumors called carcinoid tumors release certain chemicals into the bloodstream. These tumors most often develop in the digestive tract, particularly in the small intestine, rectum, and appendix.
They can also form in the lungs, pancreas, and rarely in other organs.
Most carcinoid tumors don’t cause this syndrome. In fact, only a small number release the chemicals that trigger symptoms. The liver usually filters these chemicals before they can spread throughout the body and cause problems.
However, this filtering process can be bypassed under certain conditions. The location of the tumor plays a major role in whether symptoms develop.
- Intestinal tumors: Chemicals must pass through the liver first, often getting neutralized before causing symptoms.
- Lung Tumors: Chemicals enter the bloodstream before reaching the liver, bypassing this natural filtering system.
When a carcinoid tumor spreads to the liver, the chemicals it produces can bypass this filtering process. The most important chemical released is serotonin, along with other substances like histamine, dopamine, and prostaglandins.
These substances enter the bloodstream and travel throughout the body, causing the symptoms of carcinoid syndrome.
Risk factors for developing carcinoid tumors include:
- Age: Most commonly diagnosed in adults over 60
- Family History: Certain genetic syndromes like Multiple Endocrine Neoplasia type 1 (MEN1).
- Other Medical Conditions: Conditions affecting stomach acid production may increase risk.
Only about 10% of people with carcinoid tumors develop carcinoid syndrome. The syndrome is more likely to occur when tumors have spread beyond their original location, particularly to the liver.
Complications
Carcinoid syndrome can lead to several serious health problems when not properly managed. The excess hormones produced by carcinoid tumors may damage heart valves over time.
This damage is called carcinoid heart disease and affects about 20% of people with carcinoid syndrome. The damage typically involves the right side of the heart, causing the valves to thicken and leak.
People with carcinoid syndrome may develop skin problems beyond the typical flushing episodes. Some experience telangiectasia, which are small, dilated blood vessels visible near the skin surface.
Others may notice changes in skin texture or color in areas frequently affected by flushing.
Digestive complications often occur with carcinoid syndrome. The frequent diarrhea can lead to dehydration, electrolyte imbalances, and malnutrition. Some patients struggle to maintain a healthy weight due to these digestive issues.
Carcinoid crisis represents a life-threatening complication that can happen spontaneously or during times of stress, such as surgery.
This dangerous condition involves severe flushing, breathing difficulties, rapid heart rate, and dramatic blood pressure changes. Without immediate treatment, carcinoid crisis may be fatal.
Bone problems may develop in some cases. The hormones produced by carcinoid tumors can affect bone density, potentially leading to osteoporosis or an increased risk of fractures.
