What is IgG4-Related Disease (IgG4-RD)?
IgG4-related disease (IgG4-RD) is a chronic illness that causes swelling and damage in various parts of the body. It occurs when the immune system mistakenly attacks healthy organs. This disease can lead to lumps or swelling in different areas and may be confused with infections, cancer, Sjogren’s Disease or Sarcoidosis. Although IgG4-RD predominantly affects men aged 50-70, it can occur in anyone. The exact cause remains unknown, but early treatment can help prevent severe damage.
The Most Frequent Symptoms of IgG4-RD
Symptoms of IgG4-RD can vary among individuals and may fluctuate over time. Common symptoms include:
- Pain in affected areas
- Swelling of organs or glands
- Fatigue and low energy
- Digestive issues, such as nausea or stomach pain
- Unexplained weight loss
What Organs Are Involved In IgG4-RD
Given its ability to impact multiple organs, diagnosing IgG4-RD can be challenging. Key organ systems that may be affected include:
- Salivary and lacrimal glands: Swelling, dry mouth, and dry eyes
- Pancreas: Autoimmune pancreatitis and digestive issues
- Biliary tract: Sclerosing cholangitis leading to jaundice
- Kidneys: Tubulointerstitial nephritis and impaired kidney function
- Lungs: Inflammation causing breathing difficulties
- Retroperitoneum: Fibrosis obstructing the urinary tract
- Orbits (eyes): Swelling, bulging eyes (proptosis), and vision issues
- Lymph nodes: Swelling in multiple areas
Diagnosing IgG4-RD
Diagnosing IgG4-RD requires various tests, as the disease can mimic other conditions. These tests are also used to monitor the disease and detect flares, when symptoms worsen suddenly.:
- Blood tests: Check for elevated IgG4 antibody levels, though not all patients exhibit high levels.
- Scans (X-rays, CT scans, MRIs, PET scans): Detect lumps or swelling inside the body.
- Tissue biopsy: Examine affected tissue under a microscope for signs of IgG4-RD.
Treating IgG4-RD
IgG4-RD is an ongoing condition that needs to be closely watched. Without treatment, IgG4-RD can worsen and cause permanent organ damage. Adhering to the doctor's treatment plan is crucial. While there is no cure for IgG4-RD, treatment focuses on managing the disease. As of March 26th 2025, there are no FDA-approved treatments for IgG4-RD, so a doctor may prescribe other therapies:
- Steroids (like prednisone): Common first treatment to reduce swelling and pain. Long-term use may cause side effects like weight gain, weak bones, and high blood sugar.
- Other immune system medications
(like azathioprine or mycophenolate mofetil): Some people need medicine that helps calm the immune system
- Biologics (like rituximab): Used for patients who don't respond to steroids or cannot take them long-term.
- Clinical trials: Researchers are exploring new treatments to improve care for IgG4-RD patients.
Who Treats IgG4-RD?
Since IgG4-RD can affect many organs, multiple specialists may be involved or required to manage IgG4-RD, including:
- Rheumatologists: Autoimmune disease experts
- Gastroenterologists: Specialists for stomach, pancreas, or liver issues
- Nephrologists: Kidney specialists
- Ophthalmologists: Eye-related issue experts
- Pulmonologists: Lung specialists
- Hematologists: Blood disorder experts
- Primary care doctors: Coordinate care and monitor overall health
Living with IgG4-RD
Managing IgG4-RD involves proactive measures:
- Report new symptoms: Do not ignore pain, swelling, or other changes.
- Track flares: Recording symptoms can help doctors identify patterns.
- Communicate with loved ones: Informing family and friends about the condition can provide support.
- Stay informed: Keep up with new treatments and research on IgG4-RD.
Is IgG4-Related Disease an Autoimmune or Autoinflammatory Arthritis Disease?
Right now, IgG4-related disease (IgG4-RD) is not officially classified as an autoimmune or autoinflammatory arthritis disease. Scientists are still learning how this disease works, and there isn’t enough evidence yet to say for sure if it’s an autoimmune condition. While arthritis (joint inflammation) can sometimes happen in people with IgG4-RD, it is usually not a main symptom. The disease more commonly affects organs like the pancreas, kidneys, salivary glands, and lungs.
Why is AiArthritis Raising Awareness About IgG4-RD?
At AiArthritis, we focus on helping people who live with autoimmune and autoinflammatory arthritis diseases — especially those who are still waiting for answers. That includes people who may have been misdiagnosed or not diagnosed at all.
IgG4-related disease (IgG4-RD) is not currently classified as an AiArthritis disease. However, some of its symptoms can look very similar to those in our community, like dry mouth, swollen glands, or even joint pain. Because of these similarities, IgG4-RD is often misdiagnosed as other conditions like Sjögren’s disease or sarcoidosis — two diseases we commonly hear about from patients in our community.
That’s why we’re working to bring more attention to IgG4-RD.
AUTO + Inflammatory Arthritis = X or YZ
One projects is called
AUTO + Inflammatory Arthritis = X or YZ. It’s designed to help people and their doctors figure out what’s really going on when symptoms don’t quite add up. This project was also heavily based on findings from our
AiArthritis Early Symptoms Study used to collect data on symptoms in early disease to educate health care professionals and encourage early detection and treatment.
- In this project, “X” represents a known autoimmune or autoinflammatory arthritis disease (like rheumatoid arthritis or psoriatic arthritis).
- But sometimes, symptoms don’t fit just one disease. So “Y” or “Z” could be something else, like IgG4-RD or fibromyalgia.
This project helps us look deeper at overlapping or similar conditions, so people get the right diagnosis faster — and feel better sooner.
Helping the Undiagnosed – Our “Mystery Patient” Mission
One of our biggest goals this year is to shine a light on undiagnosed or “mystery patients.” These are people who are clearly sick, but they don’t yet have a name for their disease. That can be a scary and frustrating place to be.
At AiArthritis, we’re working hard to create guidance and resources that help mystery patients expedite diagnosis and get the right treatment. By raising awareness about conditions like IgG4-RD, we hope to make it easier for people to find answers — even if their condition is rare or misunderstood.
You can learn more about our AUTO + Inflammatory Arthritis = X or YZ project and our efforts to support undiagnosed or “mystery patients” by visiting our website. Check out the page to dive deeper into the project, listen to related Talk Show episodes, and download the latest version of our Mystery Patient Guide:
www.aiarthritis.org/Equation
Even though IgG4-related disease is rare and not always easy to recognize, raising awareness can lead to faster diagnoses and better care. By learning more and sharing this information, we can help support those still searching for answers — and make sure no one feels alone on their journey.
To continue learning about IgG4-RD, check out these helpful resources:
- IGG4ward – A patient-focused organization with tools, stories, and information to support those living with IgG4-RD.
- IgG4-RD Outloud – A medical resource offering in-depth information about symptoms, diagnosis, and treatment options.
Together, we can shine a light on this often-misunderstood condition and help more people get the answers they deserve.
