What is Hashimoto Thyroiditis?
Hashimoto’s thyroiditis is an immune system disorder where the body’s defense system attacks and destroys thyroid cells. This condition is the leading cause of an underactive thyroid, also known as hypothyroidism, in developed countries. However, globally, the most common cause of hypothyroidism is not getting enough iodine in the diet. Also known as chronic autoimmune thyroiditis and chronic lymphocytic thyroiditis, this disease results from the creation of anti-thyroid antibodies that attack the thyroid tissue, causing them to slowly harden.
Diagnosing Hashimoto’s thyroiditis can be difficult and often takes some time, generally until the disease has progressed significantly. The most common lab test results show high thyroid-stimulating hormone (TSH) and low levels of free thyroxine (fT4), together with increased anti-thyroid peroxidase (TPO) antibodies. However, in the early stages of the disease, patients might show symptoms and test results of an overactive thyroid, or even normal results, because the destruction of the thyroid gland cells can happen intermittently.
Women are more likely to be affected than men, with a ratio of at least 10 to 1. Disease diagnosis commonly happens in a woman’s fifth decade of life, but the majority of women get diagnosed between the ages of 30 to 50 years. The traditional treatment involves taking levothyroxine, with a recommended dosage of 1.6 to 1.8 mcg/kg/day. The body converts this to T3, the active thyroid hormone. Overdosing can lead to harmful side effects, like arrhythmias (irregular heartbeats, with the most common one being atrial fibrillation) and osteoporosis (weak bones).
What Causes Hashimoto Thyroiditis?
The cause of Hashimoto’s disease isn’t fully understood. People with this condition usually develop antibodies that attack various elements of the thyroid gland, for instance, the most common is the anti-thyroid peroxidase (anti-TPO). Others include antithyroglobulin (anti-Tg) and TSH receptor-blocking antibodies (TBII). These attacking antibodies lead to the thyroid’s inability to produce enough thyroid hormone.
However, about 10% to 15% of individuals with noticeable Hashimoto’s disease symptoms don’t show any signs of antibodies in their blood tests. If TPO antibodies are found during the blood test, it usually signifies that the person is likely to develop the disease.
Hashimoto’s disease can be linked with Polyglandular Autoimmune Syndrome type 2, which includes autoimmune adrenal deficiency and type-1 diabetes mellitus. There’s also a connection between Hashimoto’s disease and other autoimmune conditions like pernicious anemia, adrenal insufficiency, and celiac disease.
Lastly, a study by Ruggeri and team found that Hashimoto’s disease tends to occur alongside various other autoimmune diseases not related to the thyroid, especially when the diagnosis is made in adulthood.
Risk Factors and Frequency for Hashimoto Thyroiditis
Hashimoto’s disease is the leading cause of hypothyroidism in the US and other parts of the world where people get enough iodine, particularly after the age of six. Men have an incident rate of 0.8 in 1000 each year while for women it’s 3.5 in 1000 per year. Studies looking at twins have shown that identical twins are more likely to both have autoimmune thyroiditis than non-identical twins.
- In Denmark, these studies found that 55% of identical twins both had the condition, compared to just 3% of non-identical twins.
- These findings suggest that genetics account for about 79% of the risk, leaving 21% down to environmental and sex hormone factors.
- The chance of having a thyroid disease in general goes up as people get older.
Signs and Symptoms of Hashimoto Thyroiditis
Hashimoto thyroiditis is a condition where your body’s immune system mistakenly attacks your thyroid cells. This can lead to a variety of symptoms because it can affect many different parts of your body.
First, you might experience hyperthyroid symptoms – or overactive thyroid symptoms – because the initial destruction of thyroid cells can increase the amount of thyroid hormone in your blood. But, over time, as more and more destruction happens, you might start showing signs of hypothyroidism – or underactive thyroid. These symptoms are usually subtle and can seem unrelated to each other because they can affect nearly any system in your body.
One distinctive sign of hypothyroidism is myxedema, which looks like swelling in your skin because of an increase in a substance called glycosaminoglycan. However, this symptom is very rare and usually only happens in severe cases. More commonly, you might notice that your skin becomes dry and scaly, especially on the extensor surfaces (the outside part of your elbow or knee), the palms of your hands, and the soles of your feet. An examination of your skin will show that the top layer of your skin becomes thinner. The increase in dermal mucopolysaccharides – another type of biochemical in your skin – means that your skin holds onto more water, making your skin appear pale.
Another symptom of hypothyroidism is changes to your hair. It might start growing more slowly, and it can become dry, dull, and brittle. You might also notice that you’re losing more hair than usual.
Underactive thyroid can also affect your cardiovascular system – the part of your body that controls your heart and blood vessels. You might notice that your heart slows down, but most people don’t have many symptoms related to their cardiovascular system.
Fatigue, difficulty breathing, and difficulty exercising might not only be tied to your cardiovascular system but also to your pulmonary system (lungs) and muscles. Studies have shown that people with hypothyroidism might have less physical endurance. Certain biochemical changes have been noted, like decreased oxidation in the muscles, increased use of glycogen, and decreased fat mobilization. Weakness in the muscles and muscle diseases are common in people with hypothyroidism.
You might also not display other obvious symptoms, especially in the early stages. Some early signs can include constipation, fatigue, dry skin, and weight gain. As the condition progresses, you might experience cold intolerance, less sweating, nerve deafness, peripheral neuropathy, less energy, depression, dementia, memory loss, muscle cramps, joint pain, hair loss, apnea, heavier menstrual periods, and voice hoarseness due to a swollen thyroid.
These physical signs may include:
- Cold and dry skin
- Facial swelling, especially around the eyes, and swelling in the hands and feet
- Fragile nails
- A slower heart rate
- Delayed relaxation of the tendon reflexes
- High blood pressure
- Slow speech
- Difficulty with balance
- Swollen tongue
Lastly, in some rare occasions, you might accumulate fluid in your chest and in the sac that surrounds your heart. In the most severe cases, you could enter a coma due to myxedema. This is considered an endocrine emergency and requires immediate medical attention.
Testing for Hashimoto Thyroiditis
Hashimoto’s thyroiditis is a condition in which your immune system affects your thyroid gland, leading to reduced production of a crucial hormone. This shortage is detected through high levels of a hormone called thyroid-stimulating hormone (TSH), which increases when the level of another hormone, known as free T4, is low. If tests show a low total T4 or free T4 level and a high TSH level, it means you likely have primary hypothyroidism, which is a type of underactive thyroid.
Some healthcare professionals who focus on integrative and functional medicine might also look at free T3 and reverse T3 levels, but this is not a common practice in conventional Western medicine.
Moreover, if you have this condition, you might also have anti-thyroid peroxidase and anti-thyroglobulin antibodies. However, these antibodies may not be present in about 10% of patients.
Also, approximately 30 to 40% of people with this condition have anemia. It can also cause a decrease in the glomerular filtration rate (a measure of kidney function), renal plasma flow (kidney blood flow), and renal free water clearance, leading to a condition called hyponatremia (low sodium levels in the blood).
Hashimoto’s thyroiditis can also lead to high levels of creatine kinase, prolactin, total cholesterol, LDL cholesterol, and triglycerides.
A thyroid ultrasound can be done to check the size and texture of the thyroid and spot the presence of nodules in the thyroid. It is not typically necessary for diagnosing the disease in most cases.
Treatment Options for Hashimoto Thyroiditis
The main treatment for hypothyroidism is replacing the thyroid hormone. The preferred medication is levothyroxine sodium, taken orally. Its effects last about 7 days, so it’s usually taken daily. It’s important not to take it with iron or calcium supplements, aluminum hydroxide, or medications to reduce stomach acid, as they can interfere with its absorption. It’s most effective when taken on an empty stomach early in the morning.
The typical dose is 1.6 – 1.8 micrograms per kilogram of body weight per day, but this can change depending on the patient. People under 50 are generally started on a full dose, but people with heart disease and older adults usually start on lower doses. For people over 50, the starting dose is usually 25 micrograms per day, then reviewed after six to eight weeks. Pregnant women and people with short bowel syndrome usually need to increase their dose by 30%.
There’s some debate about whether an autoimmune/anti-inflammatory diet can help. The idea is that issues with the gut lining, known as ‘leaky gut syndrome’, can let proteins into the bloodstream that shouldn’t be there. This could cause the body to produce antibodies to fight these proteins, which could mistakenly attack the body’s own thyroid peroxidase enzyme. The goal of an autoimmune diet is to help repair the gut and reduce this autoimmune response. However, more research is needed to confirm if this approach works.
What else can Hashimoto Thyroiditis be?
When examining thyroid-related illnesses, doctors take into account several possible conditions including:
- Euthyroid sick syndrome (a condition where your thyroid hormone levels are normal but the way your body uses it is not)
- Goiter (an enlarged thyroid)
- Graves disease (a condition causing excessive thyroid hormone production)
- Hypopituitarism (a condition where the pituitary gland doesn’t produce enough hormones)
- Lithium-induced goiter (an enlarged thyroid caused by lithium usage)
- Nontoxic goiter (a harmless enlargement of the thyroid)
- Polyglandular autoimmune syndrome type 1 & 2 (conditions where multiple hormone-producing glands are affected by an autoimmune disorder)
- Thyroid cancer (specifically lymphoma, a type of blood cancer that starts in cells of the immune system)
- Toxic nodular goiter (where the thyroid gland contains a small round mass or nodules that produce too much thyroid hormone)
These are considered during diagnosis to ensure that the most precise treatment plan can be put in place.
