Having one autoimmune disease is difficult enough, but some people are diagnosed with multiple autoimmune diseases over the course of their lives. This is known as overlap syndrome or polyautoimmunity. Understanding how many autoimmune diseases can coexist and what causes them to overlap provides insight into proper diagnosis and management.
What are autoimmune diseases?
Autoimmune diseases develop when the immune system mistakenly attacks the body’s own healthy tissues and organs. This leads to inflammation and damage that disrupts normal functioning. There are over 100 different autoimmune diseases that can impact any tissue or organ in the body.
Some of the most common autoimmune diseases include:
- Rheumatoid arthritis
- Lupus
- Inflammatory bowel disease
- Type 1 diabetes
- Multiple sclerosis
- Psoriasis
- Hashimoto’s thyroiditis
Autoimmune diseases are chronic and cannot yet be cured. However, symptoms can often be managed through medications that suppress the overactive immune response. Making lifestyle changes like avoiding triggers, reducing stress, and eating a healthy diet can also help.
What causes someone to develop multiple autoimmune diseases?
Researchers do not fully understand why some people develop numerous autoimmune conditions while others only ever have one. There seem to be overlapping predispositions that allow autoimmunity to target multiple areas of the body. Some potential explanations include:
- Genetic susceptibility: Many autoimmune diseases share common risk genes that make the immune system more prone to mistakes. Having a close relative with an autoimmune disease increases your odds of developing one.
- Environmental triggers: Factors like infections, gut microbes, and toxins can spark autoimmunity in those already at risk. Exposure to multiple triggers can lead to multiple autoimmune diseases developing.
- Accumulating damage: The inflammation caused by one autoimmune disease is thought to gradually trigger others over time. The immune system dysfunction becomes more generalized.
- Misdiagnosis: Symptoms of different autoimmune conditions can overlap and evolve, making them hard to distinguish. Missed or inaccurate diagnoses may incorrectly suggest multiple diseases.
How many autoimmune diseases can you have at the same time?
There is no definitive limit on how many autoimmune diseases can coexist in a single person. The range is large:
- In small studies of patients with autoimmune diseases like lupus or scleroderma, around 10-30% were found to have at least one additional autoimmune condition.
- Up to 50% of those with one autoimmune disease will eventually develop another over the course of their lifetime.
- Rare cases of patients with 5 or more concurrent autoimmune diseases have been reported in medical literature.
However, having multiple autoimmune diseases is still considered uncommon. A large 2019 study analyzing insurance records of over 30,000 patients found:
- 71% had only a single autoimmune disease
- 22% had two autoimmune diseases
- Just 7% had three or more autoimmune diseases
The higher the number of coexisting diseases, the less frequent it becomes. Nonetheless, clinicians must remain vigilant in those with autoimmunity for the potential development of additional disorders.
Which autoimmune diseases most commonly overlap?
Any combination of autoimmune diseases can occur together, but certain conditions are seen more frequently:
| Autoimmune Disease | Frequently Overlaps With |
|---|---|
| Rheumatoid arthritis | Sjögren’s syndrome, autoimmune thyroid disorders, celiac disease |
| Psoriasis | Inflammatory bowel disease, rheumatoid arthritis, uveitis |
| Type 1 diabetes | Autoimmune thyroid disorders, celiac disease, Addison’s disease |
| Multiple sclerosis | Myasthenia gravis, autoimmune thyroid disorders, inflammatory bowel disease |
| Systemic lupus erythematosus | Sjögren’s syndrome, autoimmune blood disorders, rheumatoid arthritis |
The reasons behind these common combinations are not always clear. Sometimes there are shared genetic risks between diseases, while other associations may arise from medications used to treat one condition that trigger another. Having one autoimmune disease can also make you more susceptible to developing additional immune system problems.
Which autoimmune diseases should not occur together?
There are a few pairings of autoimmune diseases that would be very unusual to see in the same patient. These include:
- Type 1 and type 2 diabetes – Type 1 is autoimmune while type 2 is not, so a patient should not have both forms.
- Autoimmune hepatitis and primary biliary cholangitis – Both cause liver damage but by different mechanisms, so it is exceedingly rare for a patient to have both.
- Pernicious anemia and atrophic gastritis – Both involve the immune system targeting stomach cells, but they typically represent different stages of the same disorder.
However, exceptions to these combinations have occasionally been documented in medical literature. There are few absolute rules when it comes to overlap syndrome, so clinicians must keep an open mind about unlikely presentations.
Are certain people more prone to multiple autoimmune diseases?
While anyone can develop more than one autoimmune disorder, certain groups have an increased risk:
- Women – Autoimmune diseases affect women more than men. Up to 75% of people with multiple autoimmune diseases are female.
- Family history – Having a relative with one or more autoimmune disorders makes you genetically susceptible.
- Young or middle age – Onset of autoimmunity often begins between ages 15-45 years.
- Existing autoimmune condition – Already having one autoimmune disease is the greatest risk factor for developing additional disorders.
- Genetic conditions – People with Down syndrome, Turner syndrome, and Type IV Ehlers-Danlos syndrome have higher autoimmune risk.
Being aware of these vulnerabilities can prompt earlier screening and recognition of multiple autoimmune diseases in a single patient.
Signs and symptoms of multiple autoimmune diseases
Some common general symptoms that should trigger suspicion of overlapping autoimmunity include:
- Unexplained fevers
- Debilitating fatigue
- Body aches and joint pain
- Skin problems like rashes or photosensitivity
- Hair loss
- Dry eyes and mouth
- Digestive issues like diarrhea or abdominal pain
- Abnormal blood cell counts
However, because autoimmune diseases can affect any bodily system, their manifestations are incredibly diverse. Patients may instead have symptoms localized to a particular organ like the kidneys, nerves, or joints.
Doctors must thoroughly evaluate all organ systems during their diagnostic workup when any autoimmune disorder is suspected. They should not prematurely zero in on one disease before considering overlap syndromes.
How are multiple autoimmune diseases diagnosed?
Diagnosing autoimmune overlap can be challenging due to the varied, non-specific symptoms that may appear sporadically over time. There is no single test that can confirm the presence of multiple autoimmune diseases.
Identifying overlap syndrome involves:
- Comprehensive medical history – Including symptoms, family history of autoimmunity, risk factors, and medication use.
- Complete physical exam – To look for any signs of disease across organ systems.
- Laboratory testing – Such as complete blood count, metabolic panel, erythrocyte sedimentation rate, C-reactive protein, antinuclear antibodies, and thyroid function tests. These assess for generalized immune dysfunction and organ damage.
- Targeted testing – Specific antibody blood tests, biopsies, or imaging scans to evaluate particular organs suspected of being impacted.
- Consulting specialists – Rheumatologists, endocrinologists, gastroenterologists, etc. can help distinguish overlapping diseases in their respective fields.
Doctors may need to treat or monitor symptoms while waiting for a clear diagnostic picture to emerge over months. Patience and persistence are key to accurately identifying multiple interconnected autoimmune conditions.
How are multiple autoimmune diseases treated?
There is no universally effective treatment for polyautoimmunity itself. Management focuses on alleviating each of an individual’s autoimmune diseases using conventional approaches:
- Medications – Corticosteroids, immunosuppressants, biologics, and organ-specific drugs tailored to the patient’s diseases.
- Lifestyle changes – Diet, exercise, stress reduction, and avoidance of environmental triggers.
- Treatment of flare-ups – More aggressive medication regimens or procedures during disease exacerbations.
- Symptomatic relief – Pain relievers, physical therapy, mental health support, etc.
Combination therapy with multiple medications is frequently needed to control widespread autoimmunity. Doctors also monitor for complications like infections or drug interactions.
A main goal is to find the minimal medication doses that keep all of the autoimmune diseases stable with the fewest side effects.
What is the prognosis for people with multiple autoimmune diseases?
Having numerous autoimmune disorders can negatively impact prognosis:
- Greater likelihood of persistent symptoms, even between flare-ups
- Increased side effects from taking multiple medications
- Higher rate of organ damage over time
- Poorer quality of life compared to having only one autoimmune disease
- Potential for drug interactions or treatment complications
However, prognosis ultimately depends on the severity of the individual diseases present and how well they respond to treatment. With aggressive management, periods of remission are possible.
Can multiple autoimmune diseases be cured?
There is currently no medical cure for autoimmune diseases, whether there is a single condition or multiple present. Treatments aim to control symptoms and limit immune attacks on the body.
In the future, emerging research into therapies like:
- Stem cell transplants to “reset” the immune system
- Antigen-specific immunotherapies that restore tolerance
- Gene therapies to correct genetic risk factors
May eventually make curative options for autoimmunity possible. But these approaches require much more study for safety and efficacy.
For now, the focus is on improving quality of life through careful management of coexisting autoimmune disorders.
Preventing the development of multiple autoimmune diseases
It can be difficult to prevent autoimmune diseases entirely, especially in those already at increased genetic risk. But several proactive measures may help reduce chances of developing additional autoimmune conditions after an initial diagnosis:
- Follow prescribed treatment plans – Keeping existing autoimmune disease well-controlled can limit cumulative immune system damage.
- Adopt a healthy lifestyle – Eating an anti-inflammatory diet, exercising regularly, not smoking, and reducing stress.
- Limit exposure to triggers – Such as infections, toxins, drugs, and physical/mental stress.
- See your doctor regularly – For screening tests and early detection of new autoimmune problems.
Being vigilant and proactive empowers patients to potentially avoid developing debilitating additional autoimmune diseases.
Takeaways
- There is no set limit on how many autoimmune diseases a single person can have, though more than three is uncommon.
- Any combination is possible, but certain conditions like rheumatoid arthritis tend to overlap frequently.
- Women, those with family history of autoimmunity, and people with one existing autoimmune disease have higher risk.
- Symptoms are highly variable, requiring extensive testing for accurate diagnosis.
- Treatment involves managing flare-ups and symptoms of each disease present.
- Outcomes depend on the diseases involved but are generally worse than having a single condition.
- Prevention focuses on controlling existing autoimmune diseases and avoiding triggers.
While still rare, overlap syndromes present unique diagnostic and treatment challenges. With a thorough workup and tailored management, outcomes for those with multiple autoimmune diseases can still be optimized.