Irritable Bowel Syndrome vs. Carcinoid Syndrome: Key Differences

Irritable bowel syndrome (IBS) is a common condition that affects the large intestine and causes symptoms like abdominal pain and cramping, bloating gas, diarrhea, or constipation, or both. Irritable bowel syndrome is a chronic condition that needs long-term management.

Carcinoid syndrome, on the other hand, happens when a rare type of cancerous tumor known as a carcinoid tumor begins secreting certain chemicals into the bloodstream.

This can cause a wide range of symptoms that are very similar to those of irritable bowel syndrome. Carcinoid tumors are often misdiagnosed as irritable bowel syndrome or as a menopause symptom in women.

It is essential to know the difference between the symptoms of irritable bowel syndrome and carcinoid syndrome to get an idea about which condition you might have and what questions to ask your doctor to determine the exact condition. Read on to know more about irritable bowel syndrome vs. carcinoid syndrome.

Irritable bowel syndrome (IBS) is an umbrella term used to describe a series of symptoms that affect the large intestine.^(1,2,3,4) It is a chronic condition that causes abdominal pain, cramping, gas, bloating, diarrhea and constipation. The cause of this condition is not clearly understood, and a diagnosis is usually made based on your symptoms.

Carcinoid syndrome is a condition that happens when a rare type of cancerous tumor known as a carcinoid tumor secretes certain chemicals into the bloodstream. This causes a wide range of symptoms.^(5,6,7)

A carcinoid tumor usually occurs in the lungs or gastrointestinal tract, and it is classified as a type of neuroendocrine tumor. Carcinoid syndrome usually affects people who have carcinoid tumors that are at an advanced stage, and treatment revolves around treating the cancer. However, carcinoid tumors do not cause carcinoid syndrome until they read an advanced stage, by when a cure is not always possible.

Over the years, doctors have gotten better at diagnosing metastatic carcinoid tumors, but even today, the wide variety of symptoms of such tumors can lead to misdiagnosis and improper treatment. According to data from the National Organization for Rare Disorders, carcinoid tumors are usually misdiagnosed as irritable bowel syndrome or other conditions like Crohn’s disease and a symptom of menopause in women.⁽⁸⁾

According to data published in the American Family Physician journal, carcinoid tumors do not cause any symptoms in most cases.⁽⁹⁾ Usually, one of these tumors is discovered by a surgeon while performing surgery for some other unrelated issue, like acute pancreatitis, diseases involved a woman’s reproductive tract or blockage of the bowel.

Carcinoid tumors secrete a variety of hormones that can affect the body, the most important one being serotonin. Increased serotonin levels in the body can stimulate the bowel, thus causing symptoms similar to irritable bowel syndrome, mainly diarrhea. Some of the other symptoms often associated with metastatic carcinoid tumors include:^(10,11)

• Muscle and joint pain
• Flushing
• Wheezing

Heart problems that can cause changes in blood pressure and irregular heartbeats, usually lowering blood pressure.

Diarrhea caused due to carcinoid tumors tends to get worse after you eat certain foods that contain tyramine. Foods that contain tyramine include cheese, wine, and chocolates.

Over a period of time, the abdominal symptoms associated with metastatic carcinoid tumors can lead to other adverse effects, including weight loss due to the stool passing through the intestines so rapidly that the body is unable to absorb any nutrients. Malnutrition and dehydration can also occur for the same reason.

Irritable bowel syndrome is a condition that primarily affects the large intestine. It causes persistent irritation that can cause constant stomach upset. Some of the symptoms associated with this condition include:

• Diarrhea
• Constipation
• Abdominal cramping and pain
• Gas
• Bloating

Some people with irritable bowel syndrome tend to experience bouts of diarrhea and constipation. Similar to metastatic carcinoid tumor, irritable bowel syndrome is usually made worse when you consume certain types of foods, including alcohol and chocolate.⁽¹²⁾ Some other foods that are known to cause the symptoms to worsen include:

• Spicy foods
• Beans
• High-fat foods
• Cruciferous vegetables like cauliflower, broccoli, and cabbage
• Dairy products

Irritable bowel syndrome typically does not cause any physical damage to the intestines. If a person experiences severe symptoms of irritable bowel syndrome, a doctor is likely to perform a biopsy of the intestine to check for disease or damage. It is usually at this stage that a doctor may discover a metastatic carcinoid tumor if there is one.^(13,14)

Looking at the similarities of the symptoms of irritable bowel syndrome and carcinoid syndrome, it is easy to understand how a metastatic carcinoid tumor gets misdiagnosed as IBS. However, there are certain factors that may cause a doctor to investigate further and order more diagnostic tests to check for a metastatic carcinoid tumor. These include:

Age at the time of diagnosis: Even though irritable bowel syndrome can be diagnosed at any age, it is more commonly observed in females younger than 45 years of age. In contrast, the average age at which a person may start seeing the symptoms of a metastatic carcinoid tumor is usually between 50 to 60 years.⁽¹⁵⁾

Weight loss: A person having irritable bowel syndrome may experience some weight loss due to diarrhea, but this symptom is more commonly observed in patients with a metastatic carcinoid tumor, or other more serious conditions. Weight loss is usually considered to be a ‘red flag symptom’ by doctors to indicate that the underlying cause of the symptoms is not irritable bowel syndrome.

Wheezing, difficulty breathing, or flushing: A person with a metastatic carcinoid tumor is more likely to experience both diarrhea and wheezing, but chalk them up to different conditions. For example, they are likely to blame the diarrhea on irritable bowel syndrome and the wheezing on a cold. However, the symptoms associated with carcinoid tumors do not always affect just one system in the body. Knowing this is important because it typically explains all the unusual symptoms you have been experiencing, even if they appear to be unrelated. In fact, flushing and diarrhea have been noted to occur at the same time in almost 58 percent of people with a metastatic carcinoid tumor.⁽¹⁶⁾

Persistent abdominal symptoms: Usually, people with a metastatic carcinoid tumor will experience different abdominal symptoms for several years without getting a proper diagnosis. If you find that your symptoms have not responded to any treatment, or they seem to improve only when you remove tyramine-containing foods and drinks from your diet, this is usually a sign that you should ask your doctor to continue examining further. Some diagnostic tests that can be helpful in diagnosing a metastatic carcinoid tumor include:

• Testing your blood for the presence of a compound known as chromogranin-A.
• Measuring your urine for 24 hours to check for 5-HIAA, which is a byproduct of the body when it breaks down serotonin.
• Make use of imaging scans like MRI and CT scans to identify the site of a metastatic carcinoid tumor.

On average, it takes about nine years from the time you first experience the symptoms of a metastatic carcinoid tumor to getting a diagnosis. While this is a very long time, but it is also an indication of just how challenging it can be to diagnose such a condition. If you are experiencing symptoms that go beyond diarrhea and the usual signs of irritable bowel syndrome, you should speak to your doctor about undergoing a complete workup for a metastatic carcinoid tumor. Most people with a metastatic carcinoid tumor do not seek treatment until the tumor has already reached an advanced stage and spread to other parts, and starts to cause additional symptoms. However, by taking steps to get further diagnostic tests done early on, which leads to a successful diagnosis of metastatic carcinoid tumor, there is a good chance that your tumor can be removed, thus preventing the condition from getting worse and spreading.

References:

Also Read:

• Irritable Bowel Syndrome (IBS): Classification and Types, Pathophysiology, Etiology, Risk Factors, Symptoms, Signs, Treatment, Investigations
• Is Irritable Bowel Syndrome Dangerous?
• Is Green Tea Good for Irritable Bowel Syndrome?
• Are Apples Good for Irritable Bowel Syndrome?
• How Do You Get Rid of Irritable Bowel Syndrome?
• Is There a Cure for Irritable Bowel Syndrome?
• Do Probiotics Help Irritable Bowel Syndrome?