What Are Autoimmune Diseases?

Do you feel tired and achy? Is it because of stress? Or could there be an underlying condition causing these symptoms, such as an autoimmune disease?

A healthy immune system defends the body from disease and infection by attacking viruses and bacteria, which contain antigens. The immune system produces antibodies to destroy these harmful substances. An autoimmune disease occurs when the immune system malfunctions and mistakenly attacks healthy tissue and organs.

No one knows what causes autoimmune diseases, but certain genes may make some people more likely to develop this problem. You can't catch an autoimmune disease from other people. However, certain chemicals, microorganisms (viruses and bacteria) and drugs may trigger changes that confuse the immune system, especially if your genes are more prone to a particular autoimmune disease.

More than 80 types of autoimmune diseases may affect one or more organ or tissue types. An autoimmune disorder may destroy body tissue, cause abnormal growth of an organ and change organ function.

Although symptoms differ based on the part of the body with a faulty immune response, common symptoms include:

  • Fatigue
  • Fever
  • Malaise or a general feeling of discomfort or illness
  • Joint pain
  • Rash

Symptoms of autoimmune diseases usually come and go. When symptoms get worse, it is called a flare-up.

Some of the most common autoimmune diseases include:

Addison disease - occurs when the adrenal glands do not produce enough hormones including glucocorticoid, mineralocorticoid and sex hormones responsible for performing important bodily functions, such as:

  • Turning food into energy and managing blood sugar levels
  • Balancing salt and water
  • Keeping blood pressure normal
  • Responding to illness and stress (your "fight or flight" response)
  • Timing when and how fast a child develops sexually
  • Supporting pregnancy

Celiac disease-sprue - damages the lining of the small intestine that results from eating gluten, preventing the absorption of nutrients from food

Graves disease - leads to an overactive thyroid gland or hyperthyroidism, which may cause weight problems, irregular menstrual periods in women or goiter

Hashimoto thyroiditis - reduces thyroid function or hypothyroidism, characterized by an enlarged neck or presence of goiter, intolerance to the cold or small or shrunken thyroid gland

Multiple sclerosis - affects the brain and spinal cord, causing nerve signals to slow down or stop

Myasthenia gravis - occurs when the body produces antibodies that block the muscle cells from receiving messages from the nerve cells that can lead to voluntary muscle weakness

Pernicious anemia - occurs when the intestines cannot properly absorb vitamin B12 which may lead to decreased red blood cells that provide oxygen to body tissue

Reactive arthritis - occurs predominantly in men between the ages of 20 and 40 following an infection in the urethra after unprotected sex, which may cause inflammation of the eyes, skin and urinary and genital systems

Rheumatoid arthritis - leads to long-term inflammation of the joints, surrounding tissue and other organs

Systemic lupus erythematosus - affects the skin, joints, kidneys, brain and other organs, which may cause joint pain and swelling that may come and go

Many autoimmune diseases have similar symptoms, making them hard to diagnose. Treatments depend on the condition and symptoms. Most autoimmune diseases are chronic and may need lifetime treatment. With proper medical treatment, a person with an autoimmune disorder can control the autoimmune process, maintain the body's ability to fight disease and reduce symptoms.


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