What Are Autoimmune Diseases?
Medically reviewed by David Ozeri, MDMedically reviewed by David Ozeri, MD
Autoimmune diseases are a case of mistaken identity in which the body's immune system, which ordinarily attacks intruders like viruses and bacteria, attacks itself. There are more than 100 different autoimmune diseases, some of which involve a single organ (e.g. Hashimoto's thyroiditis) and others that attack nearly any organ or tissue (e.g. lupus).
Early symptoms, such as fatigue and joint pain, mimic those of other medical conditions, making diagnosis challenging. These conditions can be temporary or, more commonly, lifelong. They're sometimes referred to as "invisible disabilities," since people may not appear outwardly ill despite dealing with significant issues.
Autoimmune diseases affect more than 23.5 million Americans, and more and more diseases are now being attributed to autoimmunity.
Verywell / Emily Roberts
Background
The immune system protects us from viruses, bacteria, foreign substances, and even cancer cells, but does so with a delicate balance. Without a good immune response (an underactive immune system), even minor infections could be deadly. That said, an overactive immune response (as with autoimmune diseases) can lead to illness and possibly death.
The Immune Response
When, say, a virus enters the body, it mounts an immune response. Lymphocytes and other immune cells rush to the rescue, creating inflammation. T lymphocytes are part of the innate response and function to eliminate any type of intruder. B lymphocytes are part of the learned response and produce antibodies that specifically target the threat.
Ordinarily, the immune system does not attack the body's own cells, and there are several regulatory steps (such as T helper cells) that work to prevent autoimmunity. But it does happen.
The Autoimmune Response
There are several different ways in which an autoimmune reaction may be created. These include:
When a foreign substance or microbe resembles the body: An example of this is rheumatic fever, in which proteins found in group A strep bacteria resemble proteins in the heart muscle; as a result, antibodies attack the heart.
When normal body cells are altered: An example of this mechanism is a virus altering a body cell so that it is recognized as "non-self" by the immune system.
When immune cells that make antibodies (B cell lymphocytes) malfunction and make abnormal antibodies that attack normal cells in the body
When a substance in the body that is normally hidden from the immune system (such as the fluid within the eye) enters the bloodstream and triggers a response
Takeaway
Autoimmunity does not necessarily mean autoimmune disease. For example, the body may produce antibodies against itself (autoantibodies) that are involved in cleaning up debris after an infection. With an autoimmune disease, the reaction causes inflammation and tissue damage.
Related: Autoimmune Diseases That Can Be Fatal
Types of Autoimmune Diseases
Autoimmune diseases can affect a single organ or multiple organs. Each disease is characterized by unique antibodies that detect and target specific proteins on cells called antigens. Some of these antigens reside on a single organ (causing an organ-specific autoimmune disease), while others exist on many organs (causing a systemic or generalized autoimmune disease).
Organ-Specific Autoimmune Diseases
Some of the more common organ-specific autoimmune diseases include:
Autoimmune Thyroid Disease
Autoantibodies may result in the destruction of thyroid tissue and hypothyroidism, as with Hashimoto’s thyroiditis, or in the stimulation of thyroid tissue and hyperthyroidism, as with Graves’ disease. With both of these conditions, the symptoms may develop rapidly or occur slowly over time. Autoimmune thyroid disease is very common and thought to be greatly under-diagnosed.
Hypothyroidism may cause symptoms including fatigue, weight gain, constipation, and hair loss, and the condition is treated with lifelong thyroid hormone replacement medication.
Hyperthyroidism, in contrast, often causes nervousness, anxiety, sweating, and heat intolerance, and it may be treated with antithyroid drugs, surgery, or radioactive iodine therapy to destroy the gland.
Type 1 Diabetes Mellitus
Type 1 diabetes, which often arises during childhood or young adulthood, occurs when autoantibodies destroy the beta cells in the pancreas that are responsible for making insulin. Symptoms may include thirst, increased urination, and when severe, diabetic coma.
Type 1 diabetes is treated with lifelong insulin replacement, and careful monitoring is needed to avoid complications such as kidney failure, retinopathy, and heart disease.
Psoriasis
Psoriasis occurs when the immune system erroneously sends signals to skin cells to grow too rapidly. There are several forms of psoriasis, the most common being plaque psoriasis. Plaque psoriasis is characterized by raised (often itchy) red patches called plaques that occur most frequently on the knees, lower back, scalp, and elbows.
The treatment options for psoriasis depend on the type and severity. For those who have psoriasis, it is important to screen for a related autoimmune condition called psoriatic arthritis.
Multiple Sclerosis
Multiple sclerosis (MS) is a condition in which something causes the body's immune system to attack the fatty sheath (myelin) that covers the nerves and is necessary for nerves to work properly. The disease can have many different symptoms depending on the particular area of the nervous system that's affected but may include vision problems, sensory disturbances like numbness and tingling, bladder issues, weakness, loss of coordination, tremors, and more. The National Multiple Sclerosis Society explains that it is not yet known what specific environmental factors trigger MS. For that reason, MS is considered an immune-mediated disease rather than an autoimmune disease, in which the specific antigen has already been identified.
Guillain-Barré Syndrome
Guillain-Barré syndrome (GBS) is a condition in which autoantibodies attack the support cells that line nerves. It often occurs after a viral infection (and rarely, after a flu shot), and it's thought that portions of the infectious organism resemble parts of the nervous system. Miller Fisher syndrome is a subtype of GBS.
GBS often begins with weakness and changes in sensation in the feet and hands. As the condition ascends up the body, it can become life-threatening without prompt medical care. (Paralysis of the diaphragm requires respiratory support with a ventilator.)
Systemic Autoimmune Diseases
Systemic autoimmune diseases can bring about many different issues, as their effects are felt throughout the body. Examples include:
Systemic Lupus Erythematosis
Systemic lupus erythematosus (lupus) is an autoimmune disease that affects multiple organs and has widespread effects. The symptoms of lupus may include joint pain, skin rashes, kidney problems, inflammation of the lung and/or heart, anemia, increased clotting (thrombosis), memory problems, and more.
Treatment includes lifestyle measures (such as sun protection and smoking cessation) and medications such as corticosteroids, antimalarial agents, and immunosuppressive drugs.
Rheumatoid Arthritis
Rheumatoid arthritis (RA) is characterized by pain, swelling, and joint damage. Unlike osteoarthritis ("wear and tear" arthritis), the damage in RA is due to inflammation, and the symptoms are more severe.
Without early and aggressive treatment, deformity of joints usually occurs. The same joints are usually affected on both sides of the body, and the small joints of the hands and feet are often involved. In addition to joint inflammation (synovitis), people with RA may develop lumps beneath the skin (subcutaneous nodules), pleural effusion, inflammation of the lining of the heart (pericarditis), and more.
Inflammatory Bowel Disease
Inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis, refers to chronic inflammation of the digestive tract. While Crohn's disease may cause inflammation from the mouth to the anus, inflammation in ulcerative colitis only affects the colon and the rectum. Symptoms may include diarrhea, abdominal pain, bloody stools, weight loss, and fatigue.
Treatment often includes a combination of medications and surgery, as well as careful monitoring as both conditions are associated with an increased risk of developing colon cancer.
Sj?gren's Syndrome
In Sj?gren's syndrome (SJS), autoantibodies attack glands that manufacture tears and saliva. This leads to dry eyes, a dry mouth, and related consequences such as dental decay, loss of the sense of taste, and more. Joint pain and other symptoms may also occur.
For roughly half of the people with SJS, the syndrome occurs alone, while it is associated with another autoimmune condition such as lupus, rheumatoid arthritis, or scleroderma in others.
Antiphospholipid Syndrome
Antiphospholipid syndrome is a common autoimmune condition that involves autoantibodies against certain proteins in the blood, which results in abnormal clotting. It is often first diagnosed in women as a cause of frequent miscarriages or preterm births, or when blood clots and/or bruising occur without an obvious cause.
The formation of clots can also lead to heart attacks (when they occur in the blood vessels in the heart) or strokes (when clots occur in the brain).
Related: Autoimmune Diseases by Organ System
Symptoms
While the symptoms of autoimmune diseases can vary widely depending on the particular organ or organs affected, there are some symptoms that are common with many of these diseases. Since these symptoms are non-specific, they may be a sign of non-autoimmune conditions as well.
General Symptoms
General symptoms may include:
Fatigue
Low-grade fever (often a fever that comes and goes)
Weight changes
Dizziness
Muscle and/or joint pain and swelling
Difficulty concentrating
Digestive issues
A general feeling of being unwell
Symptoms often follow a relapsing and remitting (waxing and waning) course, with the disease worsening, improving, and then worsening again in an unpredictable manner. Flares may occur, which are defined as the sudden onset of severe symptoms.
Related: Symptoms of Common Autoimmune Disorders
Disease-Specific Symptoms
Specific symptoms will vary depending on the underlying disorder and may include:
Joint symptoms, such as redness, pain, and joint swelling that is more severe than would be expected with osteoarthritis
Skin rashes, such as a "butterfly rash" on the face with lupus
Vasculitis, inflammation of blood vessels that can lead to damage wherever blood vessels are affected (e.g., aneurysms)
Many autoimmune conditions are suspected based on a particular combination of symptoms, although two people can have the same diagnosis and a very different combination of symptoms.
For example, scleroderma is characterized by CREST syndrome, (the build-up of calcium in tissues), Raynaud's syndrome (in which the hands become cold and blue upon exposure to cold temperatures), esophageal dysfunction, sclerodactyly (in which the fingers resemble sausages), and telangiectasias ("spider veins").
Co-Occurrence
It's not uncommon for people who have one autoimmune disease to develop another. This can be related to a genetic predisposition or a common trigger.
Takeaway
Overall, around 25% of people who have one autoimmune disease will develop another.
An example is a combination of rheumatoid arthritis with autoimmune thyroiditis, or the combination of celiac disease with type 1 diabetes, autoimmune liver disease, or rheumatoid arthritis.
The term multiple autoimmune syndrome is used to describe people who have three or more autoimmune diseases. There are different types of this syndrome, but frequently one of the three conditions is skin-related (such as alopecia areata or vitiligo).
Related: Autoimmune vs. Immune-Mediated Disorders
Causes
There are a number of factors that are thought to underlie the development of autoimmune diseases as well as factors that are associated with an elevated risk.
Possible causes of autoimmune disease and/or flare-ups include:
Infectious diseases: It's thought that autoimmunity may occur when a component of a virus or bacteria resembles proteins in the body, or by the infection "ramping up" the immune system. Some specific microorganisms linked with autoimmune diseases include the Epstein-Barr virus (EBV), cytomegalovirus (CMV), and group A Streptococcus bacteria.
Environmental factors: Lack of sunlight, vitamin D deficiency, chemical exposure, and other environmental factors have been linked to different types of autoimmune diseases. A number of studies have also linked autoimmune diseases to an overly sterile environment. The "hygiene hypothesis" is a theory that people exposed to fewer antigens are more likely to have a dysfunctional, overactive immune response.
Lifestyle: Smoking appears to triple the risk of developing rheumatoid arthritis and has also been linked with other autoimmune conditions such as Graves' disease and MS. Obesity is considered a pro-inflammatory state that may account for its role as a risk factor. The Western diet (high in fat, sugar, protein, and salt) is also thought to possibly promote the development of autoimmune diseases.
Gut bacteria: More and more, research is pointing to a connection between the balance of bacteria that live in a person's digestive tract (gut flora) and a number of health conditions, including autoimmune diseases.
Genetics: Several autoimmune diseases appear to run in families to varying degrees, with research in progress looking at specific genes.
Learn More: Causes and Risk Factors of Autoimmune Disease
Risk Factors
Risk factors vary depending on the particular condition, but include:
Sex: Many autoimmune conditions are more common in women. In addition, hormonal factors can play a role in flare-ups of many of these conditions.
Age: Many autoimmune conditions first appear during the childbearing years.
Weight: Some autoimmune conditions are more common in people who are overweight, while others are more common in people who have a history of eating disorders.
Ethnicity: Different conditions vary, with type 1 diabetes being more common in White people, and severe autoimmune conditions being more prevalent in Black, Hispanic, and Native-American women.
Geography: Some autoimmune diseases such as MS, IBD, and type 1 diabetes are more common in northern latitudes, where lack of daylight can promote vitamin D deficiency.
Smoking: Tobacco use is associated with an increased risk of many of these conditions.
Medications: Some medications may increase the risk of certain conditions, such as is the case with procainamide and lupus.
Learn More: Causes and Risk Factors of Autoimmune Disease
Diagnosis
The diagnosis of an autoimmune disease can take time and sometimes several opinions. In fact, and unfortunately, the average person spends four and a half years (seeing at least four doctors) before a diagnosis is made.
Where to Start
It's recommended that people begin with a specialist who deals with their most prominent symptom, such as seeing a rheumatologist if joint symptoms are predominant. Additional specialists may need to be consulted thereafter.
The diagnostic process begins with a careful history, though this can be frustrating since many people have seemingly unrelated symptoms. A physical exam can sometimes suggest an autoimmune condition based on joint swelling, characteristic rashes, and more, but further testing is most often needed.
There isn't one single test that can diagnose autoimmune diseases conclusively (with rare exceptions such as with type 1 diabetes), and evaluation usually includes a number of tests including:
There are many other tests that may be recommended depending on the condition that is suspected.
Imaging studies may be used when evaluating specific symptoms related to autoimmune conditions, such as X-rays of joints that are swollen or an echocardiogram (ultrasound of the heart) if pericardial effusion is suspected.
Related: Blood Tests for Autoimmune Diseases
Treatment
The treatments for autoimmune diseases vary with the particular disease. For many of these conditions, the course is unpredictable, and treatments may need to change over time.
In general, treatment can be thought of as consisting of:
Managing symptoms: For example, non-steroidal anti-inflammatory medications (NSAIDs) may be taken to control joint pain.
Hormone replacement: For conditions such as type I diabetes or autoimmune hypothyroidism, insulin or thyroid hormone are given.
Controlling inflammation: Medications such as corticosteroids and tumor necrosis factor inhibitors (biologic drugs) are needed to control inflammation related to many autoimmune conditions.
Preventing complications: Careful blood sugar control is needed in people with type 1 diabetes to reduce complications, whereas early and aggressive treatment is needed with rheumatoid arthritis to prevent joint deformity.
Takeaway
In some cases, an autoimmune disease may be curable, but, for most, remission or control of the disease is the primary goal.
Clinical trials are also in progress looking for newer, better ways to manage these conditions.
Related: How Autoimmune Diseases Are Treated
Coping
Most autoimmune conditions are relapsing-remitting disorders. It can be hard to predict when you will feel well and when you won't. In addition, many people with these disorders appear outwardly healthy, sometimes leading to less understanding and support from friends and loved ones.
That said, there are many things that people with autoimmune disease can do themselves to better cope with the day-to-day frustration and symptoms:
Eat a healthy diet: For those who have diabetes, monitoring diet is critical. For others with an autoimmune disease, a diet that promotes healthy gut bacteria may be helpful.
Practice good sleep hygiene: Get an adequate amount of rest every night, and try to wake up and go to sleep at the same time each day.
Exercise: Mild to moderate exercise is important for most people, but not pushing it and knowing when to stop is equally important.
Practice stress management: Stress management is helpful when coping with any medical condition, and especially important with a stressful condition such as autoimmune disease.
Know your triggers: With some conditions, there are triggers that are associated with flares of the disease. It's helpful to identify them and then look at ways to reduce your exposure.
Support
Anyone coping with a serious medical condition needs support, but this is even more true for those living with "invisible diseases." In-person support groups and online support communities can be helpful, as they provide an opportunity to connect with others who are similarly coping with an unpredictable and often misunderstood condition.
Some groups are based on specific conditions, whereas others are symptom-based. The National Coalition of Autoimmune Patient Groups is a good place to begin when looking for these communities.
Related: What Types of Doctors Can Treat Autoimmiune Diseases?
If you or a loved one are coping with an autoimmune disease, it's important to be your own advocate. The journey to a diagnosis, and later to effective treatment, can be frustrating and even lonely. Fortunately, there is a great deal of research looking into both the causes and treatments of these conditions.
Learn More: Why Autoimmune Diseases Are More Common in Women
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