Hashimoto's Thyroiditis (Hashimoto's Disease): Symptoms, Causes, and Treatment

Hashimoto's thyroiditis, also called Hashimoto's disease or chronic autoimmune thyroiditis, is a condition in which the immune system makes antibodies that gradually damage the thyroid gland in the neck. It is the most common cause of an underactive thyroid (hypothyroidism) in countries where people get enough iodine, including the United States, the United Kingdom and Australia. It is far more common in women, usually appears between the ages of 45 and 55, and often runs in families. Many people are 'antibody positive' with normal thyroid function and no symptoms; over years, some move to a mild and then a full underactive thyroid, at which point symptoms such as tiredness, weight gain, feeling cold, constipation and low mood appear. Diagnosis is a blood test for thyroid-stimulating hormone (TSH), free thyroxine (free T4) and thyroid peroxidase (TPO) antibodies. If the thyroid is still working normally, no medicine is needed, only monitoring. If it becomes underactive, treatment is a daily levothyroxine tablet, with follow-up blood tests, and the outlook is excellent.

In plain words

Hashimoto's disease is when the immune system slowly harms the thyroid gland in your neck. It is the top cause of an underactive thyroid. It is much more common in women. It often runs in families. Many people have it for years with no signs. A blood test finds it. The test checks thyroid hormones and a marker called TPO antibodies. If your thyroid still works well, you do not need medicine. You just have a blood test once a year. If the thyroid slows down, you may feel tired, gain weight, feel cold, or feel low. Then the treatment is one small pill each day called levothyroxine. It puts back the missing hormone. You take it on an empty stomach. Blood tests help set the right dose. Most people feel well once the dose is right. There is no cure for the immune part, but the outlook is very good.

What is Hashimoto's Thyroiditis (Hashimoto's Disease): Symptoms, Causes, and Treatment?

Symptoms

Early symptoms

Often no symptoms at first: Many people have raised thyroid antibodies but a normal thyroid for years, with no symptoms at all. The condition is often found on a blood test done for another reason. (1) (2)
A painless swelling at the front of the neck (goitre): The thyroid can become firm and rubbery and enlarge into a goitre. In some people the gland instead shrinks over time. A goitre from Hashimoto's is usually not painful. (1) (2) (3)
Tiredness and low energy: As the thyroid slows, persistent tiredness that does not improve with rest is often the first thing people notice. (3) (2) (4)
Weight gain and feeling cold: Modest weight gain despite no change in diet, and feeling cold when others are comfortable, appear once the thyroid becomes underactive. (3) (4) (2)
Constipation, dry skin and hair, and low mood: Slower digestion, rough dry skin, brittle or thinning hair, and sadness or poor concentration are common as thyroid hormone falls. (3) (2) (4)
Heavy or irregular periods and a slow pulse: In women, periods can become heavier or less regular. The heartbeat may be slower than normal. Both usually settle with treatment. (3) (2)
A short overactive phase (hashitoxicosis): Early on, some people have a brief spell of an overactive thyroid, with a fast heartbeat, weight loss and feeling hot, as damaged cells release stored hormone. This usually passes and is followed by normal or low thyroid function. (2) (1)

Serious or emergency symptoms

Becoming very drowsy, confused or very cold (myxoedema coma): A severe, long-untreated underactive thyroid can rarely lead to myxoedema coma, with a very low body temperature, extreme drowsiness or confusion, a slow pulse and slow breathing, often triggered by cold, infection or missed medicine. Call the emergency services now: 911 in the United States, 999 in the United Kingdom, or 000 in Australia. This needs hospital treatment. (3) (4) (2)
A neck swelling that grows quickly or presses on the throat: A goitre that enlarges rapidly, or that causes difficulty swallowing or breathing, a hoarse voice or a feeling of tightness, needs prompt assessment. Very rarely a fast-growing goitre in Hashimoto's can be a thyroid lymphoma. Seek urgent same-day medical assessment. Call the emergency services if breathing is difficult. (2) (1)

Causes

Primary causes

An autoimmune reaction against the thyroid: The immune system makes antibodies, mainly thyroid peroxidase (TPO) antibodies and sometimes thyroglobulin (Tg) antibodies, and sends immune cells that slowly damage the thyroid. Over years this reduces how much hormone the gland can make. Why the immune system does this is not fully known. (1) (2) (3)
Inherited tendency: Hashimoto's often runs in families. Having a close relative with Hashimoto's, Graves' disease or another autoimmune condition raises your risk. (1) (2) (3)
Triggers that may set it off: In people with the inherited tendency, factors such as pregnancy and the months after birth, some viral infections, a large iodine load, certain medicines (including lithium, amiodarone and some cancer immunotherapy drugs) and radiation to the neck can bring the condition on or speed it up. (2) (1)

Contributing factors

Other autoimmune conditions: Hashimoto's often occurs alongside type 1 diabetes, coeliac disease, vitiligo, pernicious anaemia, Addison's disease, lupus, rheumatoid arthritis and Sjögren's syndrome. When several occur together this is sometimes called a polyglandular autoimmune syndrome. (2) (1)
Down syndrome and Turner syndrome: People with Down syndrome or Turner syndrome have a higher rate of Hashimoto's and are usually checked regularly with thyroid blood tests. (2)
Postpartum thyroiditis: In women with underlying Hashimoto's, the immune rebound after childbirth commonly causes thyroid inflammation around 6 months after delivery. This can be temporary or become lasting. (2) (1)

Risk factors

Being a woman

Hashimoto's is roughly 7 to 10 times more common in women than in men. (2) (1)

Age 45 to 55, though any age is possible

It most often appears in middle age but can affect children, teenagers and older adults. (2) (1)

Family history of thyroid or autoimmune disease

A parent, sibling or child with Hashimoto's, Graves' disease or another autoimmune condition raises your risk. (1) (3)

Having another autoimmune condition

Type 1 diabetes, coeliac disease, vitiligo, pernicious anaemia and others are all linked with a higher chance of Hashimoto's. (2) (1)

Recent pregnancy

The year after giving birth carries a higher risk of the condition becoming active. (2) (1)

A high iodine intake or neck radiation

Large amounts of iodine, for example from supplements, and past radiotherapy to the neck can both trigger or worsen autoimmune thyroid damage. (2) (3)

Diagnosis

Hashimoto's thyroiditis is diagnosed with a blood test, sometimes with an ultrasound. The doctor asks about symptoms and family history and feels the neck for a goitre. The blood tests are thyroid-stimulating hormone (TSH) and free thyroxine (free T4) to see how well the thyroid is working, and thyroid peroxidase (TPO) antibodies to show the autoimmune cause. TPO antibodies are raised in more than 9 in 10 people with Hashimoto's; thyroglobulin (Tg) antibodies are raised in about half to four in five. The pattern of results places a person in one of three stages: antibody positive with normal TSH and free T4 (no treatment, just monitoring); subclinical hypothyroidism (raised TSH, normal free T4); or overt hypothyroidism (raised TSH, low free T4). A thyroid ultrasound is used if there is a goitre or a lump, and a fine-needle biopsy is added only if a nodule looks concerning or a goitre is growing quickly. This approach is the same in United States guidance from the American Thyroid Association, United Kingdom guidance from the NHS and NICE, and Australian guidance from the RACGP.

TSH and free T4

Show whether the thyroid is working normally, mildly underactive (subclinical) or clearly underactive (overt). (1) (2) (4)

TPO antibodies (thyroid peroxidase antibodies)

A positive result confirms the autoimmune cause. It is raised in more than 90 percent of people with Hashimoto's. (2) (1)

Thyroid ultrasound

Used when there is a goitre or a lump. It shows the typical patchy, inflamed appearance and any nodules. (2) (1)

Fine-needle biopsy (only if needed)

Added only when a nodule looks concerning on ultrasound or a goitre is enlarging quickly, mainly to rule out a thyroid cancer or lymphoma. (2)

Treatment

Medication options

Thyroid hormone replacement, only when the thyroid is underactive

There is no treatment that stops the autoimmune process, and none is needed while the thyroid is still working. If Hashimoto's causes an underactive thyroid, the treatment is the same as for any hypothyroidism: a daily tablet of levothyroxine, a man-made copy of thyroxine (T4). A full replacement dose for a healthy adult is about 1.4 to 1.8 micrograms per kilogram of body weight each day, but the dose is always set and adjusted using blood tests. Older adults and people with heart disease start on a low dose, often 25 micrograms a day, that is raised slowly. Once the thyroid is underactive, levothyroxine is usually taken for life, and most people feel well on the right dose. (1) (2) (4) (3)

Lifestyle and self-care

Get the right amount of iodine, not more: Use iodised salt or a normal balanced diet, but avoid kelp, seaweed and high-dose iodine supplements, which can worsen autoimmune thyroid damage. In Australia, healthdirect notes that having the right amount of iodine in the diet may help prevent thyroid problems. (3) (2)
Be cautious with 'thyroid support' supplements and strict diets: Selenium may slightly lower antibody levels but has not been shown to change whether the thyroid stays healthy, and major guidelines do not recommend it routinely. A gluten-free diet only helps if you also have coeliac disease. Correcting a proven low iron or low vitamin D is reasonable. Discuss any supplement with your doctor, as some interact with levothyroxine. (2) (1)
Keep your monitoring blood tests: Because Hashimoto's can slowly progress, a yearly TSH check is important even if you feel well and take no medicine, and after any dose change if you are on levothyroxine. (1) (2)
Tell your doctor if you are planning a pregnancy: Antibody-positive women have a higher chance of needing treatment in pregnancy and a slightly higher miscarriage risk, so thyroid function is checked before and during pregnancy and treatment adjusted early. (1) (2)
Look after general health: Not smoking, staying active, and treating linked conditions such as coeliac disease or type 1 diabetes all support overall wellbeing. There is no diet or lifestyle change that reverses the autoimmune process. (2) (3)

Always discuss dosing and treatment changes with your own prescriber.

Possible complications

An underactive thyroid over time: The main outcome is hypothyroidism. From the mild stage, about 5 in 100 people per year progress to a clearly underactive thyroid; overall around 20 to 30 in 100 people with Hashimoto's develop hypothyroidism needing treatment. It is easily managed with levothyroxine. (2) (1)
Effects of an untreated underactive thyroid: If hypothyroidism is left untreated it can raise cholesterol and blood pressure, cause a goitre, affect fertility and pregnancy, and, rarely and at the extreme, lead to myxoedema coma. (3) (4) (2)
Pregnancy problems: Antibody-positive women have a higher risk of miscarriage and preterm birth, and of postpartum thyroiditis about 6 months after delivery. With thyroid monitoring and treatment when needed, most pregnancies go well. (2) (1)
Rare: thyroid lymphoma: Long-standing Hashimoto's slightly raises the risk of a rare thyroid lymphoma, which is why a rapidly enlarging goitre is investigated promptly. Most goitres in Hashimoto's are not cancer. (2)
Outlook: The long-term outlook is very good. People who stay antibody positive with normal thyroid function need only yearly checks, and those who become underactive do well on a daily levothyroxine tablet with monitoring. (2) (3)

When to see a doctor

Routine follow-up

Book an appointment if you have ongoing symptoms of an underactive thyroid, such as tiredness, weight gain, feeling cold, constipation, dry skin or low mood, especially if thyroid or autoimmune disease runs in your family, so a thyroid blood test and antibody test can be done. (3) (4)
See your doctor if you have known Hashimoto's and develop new symptoms, if you notice a neck swelling, or if you are pregnant or planning a pregnancy, so your thyroid can be rechecked. (1) (2)
Attend your yearly thyroid blood test even if you feel well, because Hashimoto's can slowly reduce thyroid function without obvious symptoms. (1) (2)

Seek emergency care

Call the emergency services now, 911 in the United States, 999 in the United Kingdom or 000 in Australia, if a person with a known or suspected underactive thyroid becomes very drowsy, confused or unresponsive, feels very cold to the touch, or is breathing very slowly, or if a neck swelling makes breathing difficult. (4) (2) (3)

Frequently asked questions

What is Hashimoto's thyroiditis?

It is an autoimmune condition in which the immune system makes antibodies that slowly damage the thyroid gland. It is the most common cause of an underactive thyroid in the United States, the United Kingdom and Australia. Many people have raised antibodies for years with a normal thyroid and no symptoms. (1) (2) (3)

What are the first signs of Hashimoto's disease?

Often there are none for years. The first sign may be a painless swelling at the front of the neck (a goitre). Once the thyroid slows down, tiredness, weight gain, feeling cold, constipation, dry skin and low mood appear. (1) (3) (2)

How is Hashimoto's diagnosed?

With a blood test for TSH and free T4 to check thyroid function, plus a thyroid peroxidase (TPO) antibody test to show the autoimmune cause. A thyroid ultrasound is added if there is a goitre or a lump. (1) (2) (4)

Do I need medicine if I have Hashimoto's antibodies but normal thyroid tests?

No. The American Thyroid Association is clear that if your antibodies are high but your TSH and free T4 are normal, you do not need thyroid hormone. You need a yearly TSH check, because some people slowly progress to an underactive thyroid. (1) (2)

How is Hashimoto's treated when the thyroid becomes underactive?

With a daily levothyroxine tablet, exactly as for any hypothyroidism. The dose is set with blood tests, checked 6 to 8 weeks after a change and then once or twice a year, and is usually needed for life. Most people feel well once the dose is right. (1) (4) (3)

Can Hashimoto's be cured?

No, the autoimmune process cannot be switched off, but the underactive thyroid it can cause is easily and fully treated with levothyroxine, so with monitoring the outlook is excellent. (3) (2)

Will a gluten-free diet or selenium help my Hashimoto's?

A gluten-free diet only helps if you also have coeliac disease, which is worth testing for. Selenium may slightly lower antibody levels but has not been shown to keep the thyroid healthy, and guidelines do not recommend it routinely. There is no diet that reverses the condition. Discuss any supplement with your doctor, as some affect levothyroxine absorption. (2) (1)

Can I have children if I have Hashimoto's?

Yes. Antibody-positive women have a slightly higher risk of miscarriage and are more likely to need levothyroxine in pregnancy, so thyroid function is checked before and during pregnancy and treatment adjusted early. With monitoring, most pregnancies are healthy. (1) (2)

Is Hashimoto's linked to other health problems?

Yes. It often occurs with other autoimmune conditions such as type 1 diabetes, coeliac disease, vitiligo, pernicious anaemia and Addison's disease. Long-standing Hashimoto's also carries a small increase in the risk of a rare thyroid lymphoma, which is why a rapidly growing goitre is checked. (2) (1)

Can Hashimoto's cause an overactive thyroid?

Yes, briefly. Early on, some people have a short overactive phase called hashitoxicosis, with a fast heartbeat, weight loss and feeling hot, as damaged thyroid cells release stored hormone. It usually settles, often followed by normal or low thyroid function. (2) (1)