In this article:
- What is an autoimmune disease?
- How viruses may cause autoimmunity
- Can coronavirus trigger Hashimoto's disease?
- One case of subacute thyroiditis
The COVID-19 crisis is a worldwide emergency. Of course, you may feel worried about the impact of coronavirus on you and your loved ones. Ahead, we look at the likelihood of COVID-19 triggering Hashimoto's disease, an autoimmune disorder that can cause hypothyroidism.
What is an autoimmune disease?
An autoimmune disease is a condition in which your immune system—which usually guards against bacteria and viruses—mistakenly attacks your body. Typically, the immune system can distinguish between foreign cells and your own. Still, in the instance of autoimmune disease, the immune system mistakes parts of your body, like joints or organs, as foreign. The body then produces autoantibodies to attack healthy cells.
Hashimoto's thyroiditis is one such autoimmune disease. In Hashimoto's case, immune cells mistakenly attack the healthy thyroid tissue, causing inflammation of the thyroid. If Hashimoto's thyroiditis attacks your thyroid to the point that the gland can no longer produce enough thyroid hormones for your body to function correctly, you will develop hypothyroidism.
Doctors still aren't entirely sure of the cause of autoimmune diseases. A combination of factors may determine your likelihood of developing an autoimmune disorder. These factors may include family history, environmental triggers like bacterial infections, viral or parasitic infections, hormonal factors, or immune system dysregulation.
How viruses may cause autoimmunity
Pathogenic viruses like Parvovirus B19, Epstein-Barr-virus (EBV), Cytomegalovirus (CMV), Herpes virus-6, HTLV-1, Hepatitis A and C virus, and Rubella virus may trigger autoimmune diseases. Research links these viruses to triggering chronic inflammatory or autoimmune diseases like rheumatoid arthritis, lupus, Sjogren's syndrome, multiple sclerosis, Hashimoto's thyroiditis, and more.
There are a few explanations for what causes virus-induced autoimmunity:
Molecular mimicry
Every cell in your body has markers (called antigens) that specifically identify you as being you. Traditional research suggests that viruses carry antigens that are structurally similar to those already part of your cells. These antigens activate lymphatic cells and lead to a cross-reactive response against both self- and non-self antigens.
Bystander activation
Sometimes an overactive immune response releases self-antigens and causes inflammation. Immune cells take up these self-antigens, which activate extra lymphocytes, leading to tissue destruction.
Epitope spreading
When there is a persistent viral infection, tissue damage continues, and new self-antigens continue to release. Immune cells take these self-antigens and activate lymphocytes. This lymphocyte response then spreads to other auto-reactive cells.
So, can coronavirus trigger Hashimoto's disease?
Coronaviruses are a family of viruses that may cause illness in animals or humans. In humans, several coronaviruses can cause respiratory infections ranging from the common cold to more severe diseases like Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). The most recently discovered coronavirus causes coronavirus disease COVID-19, which became a global pandemic in March 2020.
Common symptoms of COVID-19 include fever, dry cough, pain in a muscle or group of muscles (myalgia), and/or extreme fatigue. Some patients develop severe pneumonia with sepsis leading to acute respiratory distress syndrome (ARDS).
The acute respiratory distress syndrome reported in up to 20% of COVID-19 cases looks very similar to the ARDS observed in patients with MERS and SARS. This similarity is why the virus that causes COVID-19 is known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The virus is genetically related to the coronavirus responsible for the SARS outbreak in 2003, but they are not the same.
To note: viruses, and the diseases they cause, often have different names. Viruses are named based on their genetic structure to support the scientific community's work. Diseases are named to help discuss disease prevention, spread, transmission, severity, and treatment.
While this disease continues to evolve, and research races to keep up, it is suggested that SARS-CoV-2 may trigger the development of a rapid autoimmune and/or autoinflammatory dysregulation leading to severe interstitial lung disease, in genetically predisposed patients. Interstitial lung disease is a group of several lung conditions that attack the tissue and space around the lung's air sacs.
Thyroid hormones regulate virtually all human body systems through their effect on metabolism—including cardiovascular, respiratory, renal, homeostasis, vascular tone, and central nervous system. When thyroid hormone production drops, all these body processes slow down and change. Hypothyroidism can weaken the respiratory muscles and decrease lung function.
Some studies suggest that hypothyroidism may be prevalent in patients with idiopathic pulmonary fibrosis (IPF) and chronic hypersensitivity pneumonitis (CHP). Both are lung conditions in the interstitial lung disease group. However, this does NOT mean that there is research to support a link between COVID-19 and autoimmune thyroiditis (Hashimoto's).
Future studies are needed to understand the connection between COVID-19 and autoimmune diseases, including Hashimoto's thyroiditis.
One case of subacute thyroiditis
As of August 2020, there is only one case reported of subacute thyroiditis after a SARS-CoV-2 infection. Subacute thyroiditis is a temporary inflammatory disease of the thyroid gland, often resembling hyperthyroidism.
Common symptoms of subacute thyroiditis include:
- Pain or tenderness in the front of the neck
- Fever
- Weakness
- Fatigue
Other symptoms of subacute thyroiditis may include:
- Nervousness
- Heat intolerance
- Weight loss
- Sweating
- Diarrhea
- Tremor
- Palpitations
The reported patient started experiencing some of these symptoms like neck pain, fever, and increased heart rate, after recovering from a mild case of COVID-19. After thyroid blood tests and imaging, the doctors diagnosed subacute thyroiditis. After starting treatment, her thyroid function and inflammatory markers normalized in 40 days.
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A note from Paloma Health
While we work hard to bring you the most up-to-date information, Paloma Health is not a research body. We recommend that you continue to monitor the Centers for Disease Control and World Health Organization websites for reliable COVID-19 updates and information.
