What Is Hashimoto’s Disease?

Have you ever heard of Hashimoto’s disease? 

Overview

Hashimoto’s disease, also known as Hashimoto’s thyroiditis (HT), is a chronic autoimmune disease where the immune system mistakenly attacks the thyroid gland and causes damage to its tissue. The thyroid gland is located at the base of the neck and is responsible for metabolism regulation by the production of hormones.¹ In this article, we will discuss the causes, symptoms, and treatments of HT.

Causes of Hashimoto's disease

The exact cause of HT is not yet fully understood, but it is thought to be a combination of genetic and environmental factors. Studies have revealed that a family history of other autoimmune diseases - such as rheumatoid arthritis, Lupus, or Type I diabetes - increases the chance of developing HT. Over the years, research has identified multiple genes that may contribute to HT such as major histocompatibility genes (HLA), thyroid-specific genes (TG), immunoregulatory genes, and genes responsible for thyroid peroxidase antibody synthesis. These genes are involved in the regulation and function of the immune system as well as in thyroid hormone production. Variations in these genes may increase the risk of HT development.^2,3,4

Apart from susceptibility genes, an increasing number of environmental triggers have been postulated:

1. Iodine Intake: iodine is required for thyroid hormone production. Nevertheless, excessive intake can trigger HT in individuals that are genetically susceptible^5,6
2. Environmental toxins: exposure to toxins such as industrial chemicals, pesticides, or heavy metals can increase the risk of HT^7,8
3. Selenium deficiency: selenium is a nutrient essential for thyroid hormone production and immune system regulation. Its deficiency increases the risk of HT development ^9,10,11
4. Gut health: the gut microbiome is believed to play a critical role in autoimmune diseases’ development and progression. HT development may be triggered by poor gut health such as leaky gut syndrome or dysbiosis^12,13
5. Viral infections: HT risk is increased by viral infections including hepatitis C and Epstein-Barr^14,15
6. Stress: chronic stress can negatively impact the immune system and trigger HT development¹⁶

It is important to note that both environmental and genetic factors contribute to the development of HT. Moreover, several existential factors predispose  individuals to HT such as female sex, age, pregnancy, and Down’s syndrome. These will be discussed later.³

Signs and symptoms of Hashimoto's disease

HT damages the thyroid gland. Over the years, HT progresses so slowly that you may not initially notice any signs. However, the gradual decline in the production of thyroid hormone (hypothyroidism) can lead to several symptoms. In some cases, thyroid damage can result in hyperthyroidism in the early stages. In HT, your thyroid may develop into a goitre - the enlargement of the thyroid gland, which is not painful. Apart from the physical appearance, other symptoms include:^17,18,19

1. Fatigue/Low energy levels
2. Weight gain
3. Sensitivity to cold
4. Depression
5. Constipation
6. Muscle aches/weaknesses/cramps
7. Dry and scaly skin
8. Brittle nails and hair 
9. Memory and concentration problems
10. Irregular menstrual bleeding
11. Fertility problems
12. Pain or stiffness in joints
13. Tongue enlargement
14. Puffy face
15. Slow thoughts and movements
16. Low sex drive
17. Slow heart rate

Management and treatment for Hashimoto's disease

The primary goal of HT treatment is to restore normal levels of the body’s thyroid hormone. How your doctors address the disease depends on the extent of the damage to the thyroid gland and whether the disease has developed into hypothyroidism. If it has not developed into hypothyroidism, you might just need to check your thyroid hormone levels and symptoms regularly.^17,18,19

To treat hypothyroidism, most people take medication. One type of treatment is T4 hormone replacement therapy - this involves a synthetic hormone levothyroxine which will act as the T4 hormone normally produced in your thyroid. The goal is to restore levels of this hormone and improve your symptoms and is a lifetime medication. The medication should be taken every day at the same time on an empty stomach. Note that different people may need different dosages and that is decided by your doctor. Be careful not to take excessive levels of levothyroxine as this might cause diarrhoea, headaches, weakness in bones, and chest pain.^17,18,19

Certain foods, supplements, and other medications may aid in your ability to absorb levothyroxine. These include calcium and iron supplements, high-fibre foods, soy products, and medications such as cholestyramine and sucralfate. Occasionally, dietary changes can also be effective in HT management. For instance, iodine can worsen HT symptoms, therefore a low-iodine diet may be recommended. Additionally, some patients also benefit from gluten-free diets.^17,18,19

Moreover, a combinational therapy may be used where the patient is prescribed both levothyroxine and triiodothyronine (T4 and T3 hormone replacement). This is not commonly used in the UK as there is not enough evidence to suggest that this kind of therapy is more effective than just levothyroxine. However, for some patients, the combination treatment may be suggested due to a medical history of thyroid cancer.^17,18,19

FAQs

How is Hashimoto's disease diagnosed?

If you have any of the signs and symptoms discussed above, consult your GP. Initially, they  will review your medical history and conduct a physical examination. Your doctor will check your neck for a goitre and ask you for details about your symptoms. Afterward, they  will order some blood tests to check the thyroid hormone levels (T3 and T4) and thyroid stimulating hormone (TSH). If you have low levels of T4 and high levels of TSH, you may have an underactive thyroid. If you have normal levels of T4 and high levels of TSH then you may develop an underactive thyroid in the future and for this reason, you may need to repeat regular blood tests.^{17,18,19,20,21}

Less commonly, antibody tests are conducted to measure the presence of antibodies that attack the thyroid gland. In HT patients, the most common antibodies found are antithyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-Tg) antibodies. Generally, the diagnosis of HT involves a combination of symptoms, a physical exam, and diagnostic tests. If you are experiencing any HT symptoms, you must consult your doctor to help you determine a treatment plan.^{17,18,19,20,21,22}  

How can I prevent Hashimoto’s disease?

Although there is no guaranteed way to prevent HT, there are some steps you can follow to reduce the risk of developing the disease. Following a healthy and balanced diet is crucial for preventing HT - the diet should exclude processed foods to reduce inflammation and be rich in lean protein, healthy fats, and fibre. Also, foods such as seafood that are high in iodine can be helpful. Moreover, since stress can trigger the development of autoimmune diseases, you could try relaxation techniques (e.g yoga, meditation, exercise) to reduce stress and improve your health. Adequate sleep of 7-8h is also important for preventing HT. Finally, exposure to toxins such as cigarettes, pesticides, and industrial chemicals can also increase the risk of autoimmune diseases.^23,24

Who is at risk  of Hashimoto’s disease?

Certain factors increase the risk of HT. These include:¹⁸

1. Sex women 
2. Other autoimmune diseases (rheumatoid arthritis, lupus, and type I diabetes)
3. Age in middle-aged adults
4. Pregnancy
5. Family history
6. Radiation exposure
7. Excessive iodine intake

How common is Hashimoto’s disease?

The prevalence of HT varies depending on geographical location, gender, and age. In the US, the prevalence of HT is higher in women than men and has been estimated at around 1.5%.²⁵ In areas with high iodine deficiency (parts of Asia), the prevalence of HT is higher. In the UK about 15% of the population have goitres or thyroid nodules.²⁶ In 2017, the prevalence of HT in the UK was estimated to be around 2-3% of the general population, which is equal to 1.3-2 million people.^27,28

When should I see a doctor?

The signs and symptoms seen in HT are not unique to this disease, they could result from various other autoimmune diseases as well. Therefore, if you are experiencing any of these symptoms or are at risk of HT, it is important to consult your healthcare provider as soon as you can get an accurate diagnosis.¹⁸

Summary

HT is an autoimmune disorder that affects the thyroid gland and can result in fatigue, weight gain, and is a form of hypothyroidism. Blood tests are used to diagnose the disease, and treatment mainly involves hormone replacement therapy. Risk factors of the disease include a family history of autoimmune diseases, viral infections, stress, gender, and age. To prevent the disease from developing you should maintain a healthy lifestyle and diet. If you have been diagnosed with HT, it is crucial to visit your doctor for regular monitoring and consultation on your medication dosage.