Pancreatitis is when your pancreas becomes inflamed. It has several potential causes, including gallstones and heavy alcohol consumption, or alcohol use disorder. But sometimes pancreatitis happens due to autoimmune activity. This is called autoimmune pancreatitis.

Autoimmune pancreatitis isn’t common, although it may be underdiagnosed. It’s estimated to be the cause of around 4.6 to 6 percent of instances of chronic (long lasting) pancreatitis.

This article will take a closer look at autoimmune pancreatitis, its symptoms, and how it’s diagnosed and treated.

The pancreas is an organ that’s located in your upper abdomen. It produces insulin, which helps your body regulate your glucose (sugar) levels. Your pancreas also makes digestive juices that help digest the food you eat.

When your pancreas becomes swollen and inflamed, it’s called pancreatitis. Autoimmune pancreatitis happens when your immune system mistakenly attacks your pancreas.

The exact cause of autoimmune pancreatitis is unknown. It’s possible that it’s caused by an initiating event, such as a bacterial infection, in people who are genetically predisposed to autoimmune pancreatitis or other autoimmune conditions.

Types of autoimmune pancreatitis

There are 2 different types of autoimmune pancreatitis: type 1 and type 2.

Type 1 is the most common type. It’s associated with high levels of IgG4, a type of antibody, and IgG4-producing immune cells. These antibodies can attack healthy tissue in your pancreas. Other organs, such as the bile ducts, kidneys, and thyroid may also be involved.

Type 1 disease is more common in people assigned male at birth and in individuals ages 60 years and older. It’s also has a higher prevalence in people of Asian descent, according to research.

In type 2 disease, immune cells called neutrophils are found in the ducts (tubes) of the pancreas. The activity of these cells can damage the pancreas. IgG4 either cannot be detected or is found at very low levels. This type of autoimmune pancreatitis is also sometimes associated with inflammatory bowel disease (IBD).

Type 2 disease appears to affect men and women equally and primarily occurs in younger individuals, per research. It’s been mostly observed in people of European American descent.

The symptoms of autoimmune pancreatitis can include:

Abdominal pain is generally more common in type 2 disease. When it does happen in type 1 disease, it’s often mild and comes and goes.

Autoimmune pancreatitis can also cause enlargement of the pancreas as well as the appearance of noncancerous growths. These findings, along with the symptoms of autoimmune pancreatitis, can sometimes be mistaken for pancreatic cancer.

Several different methods may be used to diagnose autoimmune pancreatitis. Because autoimmune pancreatitis can present like pancreatic cancer, it’s also important to carefully rule out the presence of cancer during diagnosis.

Your doctor will first perform a physical exam and request your medical history. They’ll ask for details about:

  • your symptoms
  • any other medical conditions you have
  • whether you have a personal or family history of pancreatitis

After that, the following methods can be used to diagnose autoimmune pancreatitis:

  • Imaging. Imaging tests can provide a view of the pancreas and its ducts. This is typically done using a computed tomography (CT) scan or a magnetic resonance imaging (MRI) scan. An ultrasound may also be used.
  • Blood tests. Several types of blood tests may be used to help make a diagnosis. Examples include:
    • a test to detect and determine IgG4 levels
    • a complete blood count (CBC), which looks at the levels of different types of blood cells
    • a metabolic panel, which includes tests that assess things like blood glucose, electrolytes, and liver and kidney function
  • Biopsy. A biopsy may be done to collect a sample of tissue from your pancreas. This tissue is then examined under a microscope to look for signs of autoimmune activity.

Another method that can be used to help diagnose this condition is called a steroid test, which isn’t actually a diagnostic test. It’s a therapeutic trial.

Most people with autoimmune pancreatitis respond well to treatment with corticosteroids. These drugs reduce inflammation by working to lower the activity of the immune system. Examples of corticosteroids include prednisone and prednisolone.

Corticosteroids are available in pill or tablet form. They’re typically used for a short period of time, after which they are tapered off. This is due to the risk of side effects with longer-term use.

An older study from 2013 included 1,064 participants with autoimmune pancreatitis. It found that 99 percent of those with type 1 disease and 92 percent of those with type 2 disease went into remission with corticosteroid treatment.

Symptoms that do not respond to corticosteroids can often suggest a misdiagnosis. Pancreatic cancer often presents in a similar way to autoimmune pancreatitis.

If you have a narrowing or blockage in your pancreatic or bile ducts due to autoimmune pancreatitis, your doctor may place a stent in the duct. This is a narrow tube that’s placed into the affected duct, allowing fluids to pass through more effectively.

Autoimmune pancreatitis can relapse following treatment. Relapses are more common in type 1 disease, occurring in up to 50 percent of people with this type of autoimmune pancreatitis. Having bile duct involvement increases the risk of relapse.

If a relapse happens, additional corticosteroid treatment may be necessary. It’s also possible that a different immunomodulating or immunosuppressing drug may be used, such as azathioprine, methotrexate, or rituximab.

Another potential complication is a narrowing or blockage of the bile ducts, which can lead to worsening of symptoms like jaundice, weight loss, and nausea or vomiting. A blockage can cause its own complications, including bilirubin buildup and liver disease.

Other complications are associated with the side effects of corticosteroid treatment. These side effects can include:

Make an appointment with your doctor if you’re experiencing symptoms such as:

  • recurring or ongoing pain in your upper abdomen
  • jaundice
  • dark urine
  • pale or clay-colored stools
  • losing a noticeable amount of weight without trying
  • frequent nausea or vomiting

Your doctor will work to evaluate your symptoms to diagnose the underlying cause, which helps them recommend a treatment plan that’s appropriate for your condition.

Autoimmune pancreatitis is an uncommon type of pancreatitis in which your immune system attacks healthy tissue in your pancreas. This can lead to symptoms like jaundice, fatigue, and pain in your upper abdomen.

Corticosteroids are typically very effective at treating autoimmune pancreatitis. However, it’s still possible for relapses to happen after treatment, particularly with type 1 autoimmune pancreatitis.

If it’s not treated, autoimmune pancreatitis can cause complications. Additionally, pancreatic cancer has very similar symptoms. As such, it’s important to see your doctor if you have symptoms like jaundice, abdominal pain, or unexplained weight loss.