Hashimoto’s thyroiditis is the most common cause of hypothyroidism. It is an autoimmune disease in which the body attacks and destroys the thyroid gland. Read on to find out more about its symptoms, causes, and available treatments.
What Is Hashimoto’s Thyroiditis?
Hashimoto’s thyroiditis (also known as Hashimoto’s, chronic lymphocytic thyroiditis, or autoimmune thyroiditis) is a progressive autoimmune disease in which the body attacks and destroys the thyroid gland.
Hashimoto’s is characterized by inflammation of the thyroid gland and high levels of antibodies against thyroid enzymes. Eventually, the damage and inflammation progress to hypothyroidism, where the thyroid gland can no longer make enough thyroid hormones thyroxine (T4) and triiodothyronine (T3) [1].
Hashimoto’s Prevalence
Johns Hopkins Hospital reports Hashimoto’s thyroiditis accounted for 6% of all thyroidectomies from 1942 to 2012 [2].
The prevalence in the US is up to 4.6% and 2% in the general population [3, 4].
Additionally, Hashimoto’s is:
- 4-10 times more prevalent in females than males [5]
- Most common in whites
- Most frequent between 45 and 55 years of age [6, 5, 7]
- More common in women using Hepatitis C treatment (interferon-α) [8, 9]
- Most likely triggered by Hepatitis C virus at all ages [7]
Hashimoto’s Thyroiditis Symptoms
The following symptoms are commonly associated with ocular migraines but are insufficient for a diagnosis. Consult it with your doctor if you experience several of these symptoms for an appropriate diagnosis and treatment.
Symptoms of Hashimoto’s thyroiditis are not specific to the disease and may be confused with other autoimmune disorders. The most commonly observed symptoms include [10]:
- Cold intolerance
- Depressive mood
- Dry skin
- Puffy eyes
- Constipation
- Weight gain
- Slowed heart rate
- Joint and muscle pain
- Fatigue
- Goiter (enlarged thyroid gland)
Other autoimmune diseases may occur alongside Hashimoto’s [10, 5, 11]:
- Vitiligo
- Rheumatoid arthritis
- Celiac disease*
- Diabetes type 1
*Many patients with autoimmune thyroid disease also have celiac disease. Therefore, it may be prudent to get tested for celiac disease if some of the symptoms cannot be attributed to Hashimoto’s thyroiditis [12].
Celiac disease patients have 2-4 times increased risk of developing Hashimoto’s [13, 14, 12].
There are two forms of Hashimoto’s:
- Atrophic (associated with HLA-DR3), where autoantibodies break down the thyroid gland until it is no longer functional. where
- Goitrous (associated with HLA-DR5), the thyroid gland becomes inflamed and swollen [10].
Primary Tests for Diagnosis of Hashimoto’s
Diagnosis of Hashimoto’s thyroiditis is defined primarily by:
1) High Levels of TSH and Low Levels of Thyroid Hormones
Thyroid-stimulating hormone (TSH) is a hormone made by the pituitary gland that causes the thyroid gland to make T4. It is the most commonly tested hormone to screen for hypothyroidism before other tests are done [15, 16].
Generally, the higher the TSH levels, the lower the thyroid function [17].
The reference range is 0.27-4.2 IU/ml [18], but some studies used ranges as low as 0.2-2.5 mU/L [19].
Thyroid hormones are also tested. The normal ranges for thyroid hormones are:
- Total T3 (tT3): 4.2 to 9.1 pmol/L
- Total T4 (tT4): 10.0 to 27.2 pmol/L
- Free or unbound T4 (fT4): 0.9 to 1.7 ng/dL
- Free or unbound T3 (fT3): 2.5 to 4.3 pg/mL
2) The Presence of Thyroid Hormone Antibodies
Antibodies against four different thyroid compounds can be found:
- Thyroxine (T4): Least active form of thyroid hormone
- Triiodothyronine (T3): Most active form of thyroid hormone
- Thyroglobulin: A protein that transports T4 and T3 in the blood
- Thyroperoxidase: An enzyme that helps produce T4 and T3
People with autoimmune thyroid disease symptoms will likely test positive for at least one thyroid antibody [20, 21].
Those without thyroid diseases are not expected to have detectable levels of thyroid autoantibodies, although there are some exceptions.
Thyroid antibodies and their normal levels* [22, 16]:
- Anti-thyroxine positive at >8.0% in blood [23, 24]
- Anti-triiodothyronine positive at >8.0% in blood [23, 24]
- Anti-thyroglobulin or anti-TG at 5-40 IU/mL
- Anti-thyroperoxidase or anti-TPO at 0-35 IU/mL
*The study that defined these ranges considered anti-TPO <35 and anti-TG <40 as “negative.”
Lab results are commonly shown as a set of values known as a “reference range”, which is sometimes referred to as a “normal range”. A reference range includes the upper and lower limits of a lab test based on a group of otherwise healthy people.
Your healthcare provider will compare your lab test results with reference values to see if any of your results fall outside the range of expected values. By doing so, you and your healthcare provider can gain clues to help identify possible conditions or diseases.
Some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don’t panic if your result is slightly out of range in the app – as long as it’s in the normal range based on the laboratory that did the testing, your value is normal.
However, it’s important to remember that a normal test doesn’t mean a particular medical condition is absent. Your doctor will interpret your results in conjunction with your medical history and other test results.
Have in mind that a single test isn’t enough to make a diagnosis. Your doctor will interpret this test, taking into account your medical history and other tests. A result that is slightly low/high may not be of medical significance, as this test often varies from day to day and from person to person.
3) Ultrasound or Needle Biopsy of the Thyroid Gland
Thyroid ultrasound of individuals with hypothyroidism will likely show abnormal thyroid tissue. The doctor may also order a needle biopsy to sample the thyroid tissue and test for cancer [25, 26].
Secondary Tests for the Diagnosis of Hashimoto’s
1) Physical examination of the thyroid gland for inflammation (goiter)
A physician will examine the front of the neck to feel for evidence of swelling or goiter.
2) Urinary iodide concentration/excretion (UIC/UIE) measurements
Children with autoimmune thyroiditis between the ages of 6 to 12 have high (>300 μg/L) levels of UIC/UIE compared to healthy children and are at higher risk of progressing to clinical hypothyroidism [7, 27].
5 Stages of Hashimoto’s Thyroiditis Progression
The progression of Hashimoto’s thyroiditis can be divided into 5 different stages [15]:
Stage One: Thyroid function is normal and there are no thyroid antibodies present. However, for those who have a genetic predisposition, there may be evidence of immune activation (abnormal cell types found in serologic tests).
Stage Two: Thyroid antibodies are detected in the blood, with increasing concentration over time. Higher levels of TSH, which can lead to thyroid inflammation in predisposed people, become apparent.
Stage Three: This is subclinical thyroid dysfunction. Thyroid antibody levels continue to increase until overt Hashimoto’s thyroiditis develops.
Stage Four: This is overt Hashimoto’s thyroiditis with diagnosable hypothyroidism. At this stage, patients are at the highest risk of developing clinical hypothyroidism (non-functioning thyroid gland).
Stage Five: Complete hypothyroidism as a result of Hashimoto’s thyroiditis progression and other factors (lifestyle, genetics, etc.).
Environmental Risk Factors for Hashimoto’s Thyroiditis
There is no known single environmental cause of Hashimoto’s, but several have been associated with the development of autoimmune thyroiditis. Because the majority of studies covered in this section deal with associations only, a cause-and-effect relationship hasn’t been established. Additionally, complex disorders such as Hashimoto’s involve multiple possible factors that may vary from one person to another.
1) Postpartum Hormonal Fluctuation
Thyroid antibody concentration decreases during pregnancy to prevent rejection of the fetus. Following birth, there is a rebound in thyroid antibodies. This fluctuation of thyroid hormones puts a mother at risk of developing postpartum thyroiditis (observed in 3-8% of all pregnancies), a common forerunner of other permanent autoimmune hypothyroidisms [15, 28].
2) High Iodine Levels
The development of autoimmune thyroiditis is associated with excessive iodine exposure. Increased iodination of thyroglobulin (a protein involved in thyroid hormone production) may lead to autoimmune thyroiditis symptoms in susceptible individuals [10, 29].
Deterioration of the thyroid gland likely follows excess iodine levels [30].
3) Radiation Exposure
The prevalence of thyroid antibodies increased after the Chernobyl accident where children were exposed to radiation. This suggests that significant radioactive fallout can likely increase the risk of developing autoimmune diseases like Hashimoto’s [31].
4) Pollutants
Toxic substances, including tobacco smoke, solvents, and certain metals, have been associated with an increased incidence of Hashimoto’s [10].
5) Drugs
Certain drugs used to treat viral infection (interferon-α) or cancers (ipilimumab, pembrolizumab, and nivolumab) have been associated with autoimmune disorders, including Hashimoto’s [10, 32].
6) Sleep Apnea
Important facts about sleep apnea [22]:
- Characterized by pauses in breathing during sleep
- Causes fatigue and lethargy upon waking
- Hashimoto’s thyroiditis is prevalent in people with obstructive sleep apnea (OSA), especially among women
- People with both OSA and Hashimoto’s have elevated levels (1,000 IU/mL) of thyroid antibodies compared to people with Hashimoto’s alone (400 IU/mL)
- Associated with low-grade inflammation (inflammatory cytokines), which may accelerate the development of autoimmune symptoms seen in Hashimoto’s thyroiditis
The importance of the circadian rhythm:
- TSH follows a circadian rhythm, peaking at the beginning of sleep, while the lowest concentration occurs at midday [33, 34].
- The circadian rhythm of TSH secretion is retained despite abnormal thyroid function in Hashimoto’s patients [35].
- Abnormalities in the sleep cycle due to sleep apnea, combined with TSH rhythm, could result in excessive levels of inflammation and increase the risk for autoimmune diseases.
7) Heavy Metals
Inflammation from high antibody levels (anti-thyroid peroxidase and anti-thyroglobulin) worsens Hashimoto’s symptoms. Removal of mercury-containing dental amalgams decreased thyroid antibodies in 27 people with mercury allergies [36].
In a study of over 5,600 Chinese adults, women exposed to more cadmium had higher thyroglobulin antibody levels. Sources of cadmium exposure include cigarette smoke, processed and instant foods, and contaminated large ocean fish [37, 38].
Hashimoto’s Thyroiditis Treatment
Consult your doctor if you have symptoms of Hashimoto’s thyroiditis for a proper diagnosis. If there’s no direct evidence of abnormal thyroid hormone levels and your thyroid gland seems to be functioning normally, your doctor may suggest a “wait-and-see” approach.
Synthetic thyroid hormone replacement is the standard treatment used to restore thyroid hormone levels in the body. The most common synthetic version is levothyroxine (L-T4). The treatment is usually life-long – but because the dosage required may change, your doctor will likely continue to have your thyroid hormone levels checked every 12 months or so [39].
Taking L-T4 on an empty stomach before bedtime results in higher thyroid hormone concentrations and lower TSH levels, but for some people, L-T4 is best taken in the morning on an empty stomach. However, some studies found no differences between taking it with or before breakfast [40, 41, 42, 43].
A significant minority (12%) of patients taking levothyroxine still report lingering symptoms after treatment, possibly due to impaired conversion of T4 into its active form, T3 (due to mutations, thyroid cancer, or thyroid removal surgery). In this case, adding synthetic T3 to the L-T4 therapy may help [44].
One study of 59 hypothyroid women found that, after 12 weeks, a combination of synthetic T4 and T3 was more effective at improving quality of life, anxiety, and depression than taking T4 alone [45].
Desiccated thyroid is a supplement made from the thyroid glands of pigs and cows that is often taken to treat hypothyroidism and contains both T3 and T4.
A clinical trial on 70 hypothyroid patients found that desiccated thyroid for 16 weeks resulted in an average weight loss of 3 lbs, whereas patients taking levothyroxine experienced no weight loss. This was possibly the reason why desiccated thyroid was preferred by nearly half of the patients (34) compared to only 13 who preferred levothyroxine [46].
Talk to your doctor if you have hypothyroidism symptoms despite treatment with LT4 and discuss if these combined therapies might help in your case. Carefully follow your treatment plan and never change or discontinue it without consulting your doctor beforehand.
In addition, excessive dietary iodine has been associated with autoimmune thyroid disorders in multiple studies and doctors often prescribe a low-iodine diet for this reason [47, 48, 49, 50].
According to the American Thyroid Association (ATA), a “low-iodine” diet is typically one that is low in [51]:
- Iodized salt
- Seafood
- Seaweed
- Dairies
- Egg yolks
Carefully follow your doctor’s recommendations and never make drastic changes in your diet without consulting it with them beforehand.
Complementary Approaches to Hashimoto’s
You may try the complementary approaches for Hashimoto’s thyroiditis listed below if you and your doctor determine that they could be appropriate in your case after discussing them. Remember that none of them should ever be done in place of what your doctor recommends or prescribes.
Lifestyle
Exercise
Doing more exercise may improve how your thyroid gland works. In 2 small trials on 20 adults and 36 adolescents, exercise increased T3 and T4 while decreasing TSH levels [52, 53].
However, extenuating exercise may do more harm than good. It may reduce T3 levels and increase inflammation (Th17 immune response) [54, 55, 56].
For this reason, be sure to do moderate exercise and always speak with your doctor before starting a new exercise regime.
Reduce Stress
Stress decreases thyroid function. Repeated stress increases glucocorticoid production, which in turn reduces the levels of T3, T4, and TSH [57, 58].
Read here how to reduce your stress response.
Blue-Blocking Glasses
Melatonin is a hormone secreted by the pineal gland that controls our cycles of sleep and wakefulness. Blue-blocking glasses allow your body to create sufficient melatonin at night.
People suffering from the effects of fatigue or obstructive sleep apnea (OSA) as a result of impaired thyroid function may find blue-blocking glasses or melatonin supplementation to be an effective tool for restoring sleep cycles. Consecutive days of bright light exposure at midday increases levels of nocturnal melatonin release, which should help restore abnormalities in circadian rhythm [59].
Too much melatonin can be an issue, however. Compared with healthy individuals, melatonin secretion at midnight is higher in most people with autoimmune diseases. Consequently, higher levels of melatonin lead to inflammatory responses (increase in inflammatory cytokines) that often have adverse effects in those with autoimmune diseases [60].
High levels of melatonin have inhibitory effects on cell development and thyroid hormone synthesis [61].
Normal melatonin levels are important for achieving better sleep and lowering the intensity of autoimmune thyroiditis symptoms.
Finally, a study on the antioxidant-like effects of melatonin in pig thyroid tissue showed that melatonin may be effective in protecting against harmful DNA destruction associated with thyroid cancer initiation (Fe + H2O2-induced fat breakdown) [62].
Low-Level Laser Therapy
Hashimoto’s patients needed less L-T4 treatment after low-level laser therapy on the neck and upper chest. Additionally, anti-thyroid peroxidase levels decreased [63, 64].
Discuss with your doctor if this complementary approach may help as an add-on to your treatment regime.
Diet
Diet is a critical component of thyroid health. The following are examples of diet changes that may improve thyroid function. Remember to discuss them with your doctor and always follow their recommendations to avoid nutrient deficiencies and other unwanted effects.
1) Low-Carbohydrate Diets
Maintaining a low-carbohydrate diet may decrease the levels of antithyroid molecules and other autoantibodies (antimicrosomal, anti-thyroid peroxidase) [65].
For those dealing simultaneously with celiac disease, a gluten-free diet may prove effective in decreasing autoimmune thyroid antibodies and possibly thyroid inflammation [32, 13].
However, it is important to note that there is no unanimous conclusion on the effectiveness of gluten-free diets for people with autoimmune diseases. A year-long study on newly diagnosed celiac disease patients found that the thyroid gland continued to atrophy despite a change to a gluten-free diet [66].
Therefore, gluten-free diets may not work for everyone to prevent the development of autoimmune diseases specifically affecting the thyroid gland. Yet, be sure to check if you have gluten intolerance, since celiac disease is more frequent in people with Hashimoto’s and other types of hypothyroidism [32, 13, 67].
2) Low-Goitrogen Diets
Goitrogens are substances that reduce thyroid hormone production by limiting thyroid gland iodine uptake. Cruciferous vegetables (broccoli, cabbage, cauliflower) contain goitrogens and, at high levels of consumption, have been associated with increased risk of thyroid cancer in women with low iodine intake [68, 69].
Other foods rich in goitrogens include some cereals (sorghum, millet, maize), vegetable roots (turnip, cassava), and legumes (soybean, Lima bean) [70].
Goitrogens also cause thyroid inflammation, so a low-goitrogen diet may prove useful to people suffering from the goitrous variety of Hashimoto’s [71].
Supplements
The following supplements may also help with Hashimoto’s thyroiditis. Remember it’s preferable to take certain vitamin and mineral supplements only in cases of deficiency. Some of them may be toxic at excessive doses and even worsen hypothyroidism or brain fog. Speak with your doctor before taking these supplements.
1) Vitamin D
Vitamin D deficiency is common in Hashimoto’s thyroiditis patients, and it may be a factor involved in the progression to complete hypothyroidism. Anti-thyroxine levels decreased in Hashimoto’s patients after vitamin D (D3, cholecalciferol) replacement treatment for 2 months [72, 73].
However, it is important to note that in cases of women with postpartum thyroiditis, spontaneous decreases in autoantibodies may occur [73].
Additionally, one study reported low levels of vitami\n D in women with significant amounts of antithyroid antibodies but did not find the same negative correlation in men [15].
Therefore, some men may not benefit as much from vitamin D supplementation to treat Hashimoto’s symptoms.
2) Vitamin B12
Vitamin B12 deficiency is common (nearly 40%) in people with hypothyroidism. Vitamin B12 supplementation may reduce Hashimoto’s symptoms including fatigue and depression [74].
3) Selenium and Myoinositol
Selenoproteins are essential to thyroid function. Selenium deficiency prevents selenoproteins from removing excess hydrogen peroxide in the thyroid gland, thus resulting in inflammation and an increased risk of thyroid disease [75].
Selenium supplementation (50 to 100 μg/day) may help control autoantibody levels, thus lowering the intensity of hypothyroidism symptoms common to Hashimoto’s thyroiditis [76, 75]. However, its effectiveness is not equal for all individuals.
Additionally, a selenium-containing treatment (myo-inositol and seleno-methionine) can decrease harmful thyroid autoantibodies [77].
4) Iron
Iron deficiency prevents proper thyroid function. Special iron-containing proteins (thyroid peroxidases) help produce thyroid hormones, but when iron levels are low, hormone production is reduced too. Iron supplementation treatment may be especially relevant to anemic women with Hashimoto’s thyroiditis. Thyroid hormone concentrations can be restored in anemic women with impaired thyroids after iron supplementation [75].
