by Christopher M. Cirino DO, MPH and Julian Dollente, RN

The Most Common Cause of Hypothyroidism is Autoimmune

For those of you who have hypothyroidism, which is about 5% of the US population, you will find this article useful. An autoimmune cause of thyroid dysfunction accounts for 90% of hypothyroidism. Knowing that your hypothyroidism has autoimmune causes is necessary, because it may mean that you are at risk of developing other conditions.

The condition Hashimoto’s Thyroiditis (HT) is an autoimmune disorder that leads to a low functioning thyroid, or hypothyroidism. It is the most common cause thyroid disorder and affects about 1 in 50 people in the US. It is caused when a certain type of white blood cell invades the thyroid tissue, leading to inflammation and scarring. The process may wax and wane over years, showing excess functioning at times, until it ultimately progresses to hypothyroidism. For a deeper dive into HT, refer to this YHF article.

Diagnosis and Genetic Associations of Hashimoto’s thyroid disease

In the clinical setting, a person may be identified as having bloodwork consistent with thyroid dysfunction. They may have had complaints of fatigue, weight gain, cholesterol issues, or multiple of other symptoms. In that case, it is likely Hashimoto’s disease, which can be confirmed if your doctor check for elevated levels of thyroid peroxidase Ab (TPOAb) and thyroglobulin Ab (TGAb). These antibodies are found in 85-90% of those with HT. The presence of TPOAb and TGAb does correspond to an increase incidence of other autoimmune diseases.

Aside from other putative links, Hashimoto’s thyroiditis has a genetic risk factor. Individuals with HT may develop conditions to some frequency as to suggest a similar genetic origin. The coexistence of other autoimmune conditions is known as polyautoimmunity. Sometimes there may be multiple conditions that aggregate. These are referred to as Autoimmune polyglandular syndromes (APS). For instance, a person with APS type 2 has thyroid (HT), adrenal (Addison’s), and pancreatic dysfunction (Type 1 diabetes).

7 Conditions Associated with Thyroid Disease

Below is a list of seven conditions that may be associated with HT:

Addison’s Disease

Addison’s disease is also known as primary adrenal insufficiency. Like Hashimoto’s, it is also an autoimmune disorder where the immune system attacks and destroys the adrenal glands, leading to insufficient cortisol and aldosterone hormone production. Its symptoms may include fatigue, nausea, weight loss, darkened skin, salt craving, and dizziness. Addison’s disease is not a common condition, but patients with Hashimoto’s are ten times more at risk. 

Graves’ Disease

Graves’ disease is functionally the opposite of Hashimoto’s. The condition leads to overproduction of thyroid hormones, leading to hyperthyroidism. The immune system generates antibodies that cause the thyroid to grow and produce excess hormone. These are called Thyroid-Stimulating Immunoglobulins (TSIs). 

While it may seem paradoxical for someone to have both Hashimoto’s (hypothyroidism) and Graves’ disease (hyperthyroidism), alternating or combined disease occurs, albeit rarely.

Pernicious Anemia

People with hypothyroidism are 20 times more likely to having pernicious anemia. autoimmune disorder prevents the absorption of vitamin B12, which is crucial in producing red blood cells. Doctors screen for pernicious anemia by checking blood tests that suggest B12 deficiency. The most reliable way to screen is bloodwork for methylmalonic Co-A and Homocysteine, which are elevated if B12 is deficient. To diagnose pernicious anemia, a GI doctor can check intrinsic factor and parietal cell screening. 

Celiac Disease

It is possible for a person with Hashimoto’s to also have Celiac disease, a problem on the immune system that revolts against gluten. A study found an association of celiac disease in  9.3% of women with thyroid disease of them also have celiac disease. Staying away from gluten foods and starting a gluten-free diet may help decrease specific symptoms of Hashimoto’s.

Rheumatic Arthritis

Rheumatic arthritis is another autoimmune disorder that inflames the joints and has other findings in the body. This disease may involve organs like the eyes, skin, and heart. Rheumatoid arthritis affects 1.3 million of the population in the United States, and 70% of them are women. People with rheumatic arthritis may develop thyroid disease like Hashimoto’s Thyroiditis. 

A study in 2017 discovered that about 15.7% of people with thyroid disease also have rheumatic arthritis. People who have both autoimmune disorders can manifest muscle aches, tenderness, swelling of small joints of the hands and feet.

Fibromyalgia

Fibromyalgia is a musculoskeletal syndrome characterized by pain, tenderness, fatigue, and other body symptoms. Studies suggest disruption in the endocrine system leading to an increased stress response. Although fibromyalgia is seen in 2-7% of the general population, the rate increases to 30-40% of those with HT. These patients were more likely to have antithyroid peroxidase antibody (TPO Ab) (Haliloglu et al., 2017). The correlation of the two diseases suggests an autoimmune role of fibromyalgia and warrants screening for hypothyroidism in the setting of this condition (Sarzi-Puttini, 2021).

Vitiligo

Vitiligo is a disease of patchy pigmentation loss from an autoimmune attack on melanocytes. It associates with thyroid disease along with many of the other conditions mentioned above. One study found more autoimmune thyroid disease in patients with vitiligo than controls, 21% versus 3% (Zettinig, 2003). Since it can be found easily on an exam, screening for thyroid disease, and the thyroid autoantibodies, should be considered in anyone with vitiligo.

Other Associations

HT has also been associated with other autoimmune conditions, including Systemic Lupus Erythematosus (SLE) and Sjogren’s syndrome (SS).

Suggestions for Those with Hypothyroidism

Hashimoto’s thyroiditis is a condition that often gets diagnosed when a person develops symptoms of hypothyroidism. It is not routine practice to check for autoantibodies to confirm HT, but it might be a useful clue to determining if you are at risk of another condition. Hashimoto’s thyroiditis is the most common thyroid disorder.

Additionally, studies have indicated that inflammation, such as a result of toxic stress, sleep deficiency, simple sugars and ultra-processed carbohydrates, may lead to an epigenetic changes that contribute to the expression of autoimmune diseases.

It is estimated that 20% of what diseases we develop in life are from inherited disease. An overwhelming majority 80% are a result of the environment switching or off epigenetic expression. In summary, you have the power to affect, mitigate, and even prevent your disease.

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References

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Anaya JM, Shoenfeld Y, Rojas-Villarraga A, et al., editors. Bogota (Colombia): El Rosario University Press; 2013 Jul 18. Chapter 30. Autoimmunity: From Bench to Bedside. [Internet]

Morris B. Hashitoxicosis: An Uncommon Presentation of Autoimmune Thyroid Disease. Proceedings UCL Healthcare. 2013. Vol 17.

Weetman AP. Diseases associated with thyroid autoimmunity: explanations for the expanding spectrum. Clinical Endocrinology. 2010. Vol 74(4): 411-418.