Hashimoto’s disease is a condition in which the body’s immune system starts to attack the thyroid gland. The thyroid gland can be damaged due to the inflammation caused by antibodies attacking it and this may result in some swelling of the thyroid gland. It may stop the thyroid gland working well causing hypothyroidism (low levels of thyroid hormones).
The main cause behind the development of Hashimoto’s thyroiditis is unclear although a combination of different factors is likely to contribute. Some people are more prone to it than others probably due to their genes since this type of thyroid disease (termed “autoimmune”) is known to run in families. When these people are exposed to certain precipitating environmental factors, their bodies start producing some proteins called antibodies.
Antibodies usually recognise and remove foreign substances such as bacteria or viruses but, occasionally, for reasons not well understood, they perceive a part of our body as “foreign” and mount an attack against that area, for example the cells within the thyroid gland. This causes a type of inflammation called thyroiditis following which the thyroid gland may start malfunctioning.
Hashimoto’s disease tends to develop gradually over a long period of time. The thyroid gland usually is not painful however, it can be swollen and rubbery to touch (goitre) or in some cases, it can be normal in size or smaller (atrophied thyroid).
Symptoms and signs are variable and non-specific amongst different individuals depending on the degree of thyroid malfunction. They can range from very few or none if the thyroid gland is only mildly affected (subclinical hypothyroidism) to several of them if the levels of thyroid hormones are low or very low (underactive thyroid or hypothyroidism). Less commonly, some patients may develop initially an overactive thyroid phase (hyperthyroidism) that is short lived.
Some of the symptoms people might experience include: dry skin, brittle hair, weight gain, general fatigue, hoarseness and intolerance to cold weather. Low mood, poor concentration and forgetfulness are also common. The heart and lungs can be affected causing fluid retention, breathlessness and decreased tolerance to exercise. Bowel movements can slow down causing constipation and the joints and muscles can feel weak, stiff, achy or painful. Carpal tunnel syndrome can also develop and usually improves with treatment. Women may notice a change in their periods, usually becoming heavier than normal.
Hashimoto’s disease causing hypothyroidism is found in approximately 2% of the population, although its occurrence increases with age. It is more common than hyperthyroidism (an overactive thyroid gland). Women are between five to eight times more likely to be affected than men, especially older women. Hashimoto’s disease is also the commonest cause of hypothyroidism in children.
Although the disease itself is not inherited, autoimmune diseases tend to run in families. It is also likely that a patient with Hashimoto’s disease may have some other autoimmune disease.
Usually if Hashimoto’s disease is suspected due to the signs and/or symptoms a patient develops, a blood test is arranged. This blood test will measure the level of thyroid hormones mainly TSH (thyroid stimulating hormone) and T4 (thyroxine). The level of TSH is the most sensitive indicator of thyroid function. When it is high, this indicates that the thyroid gland is not producing enough thyroid hormones, as in Hashimoto’s disease. When the thyroid gland is overactive, as occurs in Graves’ disease, the thyroid stimulating hormone level is low. Antibodies to the thyroid gland can also be measured in blood tests, although not every person with antibodies will develop a serious thyroid disease. These tests can be carried out either at the GP practice or outpatient departments.
A thyroid gland scan is rarely needed. However, if the thyroid gland is unevenly swollen, the doctor may request a scan to determine if there are any thyroid nodules or other abnormalities that might need a small biopsy with a needle (fine needle aspiration) to look at the cells. The doctor may also request additional blood tests to check if there are any other associated autoimmune conditions.
Treatment is carried out as an outpatient and depends on how well the thyroid gland is working.
Lifelong levothyroxine tablets are needed to treat hypothyroidism because they replace the hormones that the thyroid gland is no longer producing in sufficient quantities. Blood tests to measure thyroid hormones will be needed to ensure the dose is correct. This is arranged initially every few weeks, then less often, once the right dose has been determined. The doctor will advise on the right course of treatment for each individual case.
Doctors often have a lower threshold for commencing thyroid hormone replacement in women with mild Hashimoto’s disease who are pregnant, or planning pregnancy.
Very rarely, thyroid surgery can be required especially if the thyroid gland is very swollen making difficult to eat or breath or if the cells obtained with a fine needle aspiration show lymphoma or other suspicious cancer cells.
If thyroxine replacement is monitored adequately and the dose is kept stable, there should be no side-effects.
Patients whose thyroid function stays stable after the bout of inflammation have a risk of developing hypothyroidism in the long run. They should discuss any concerns they have with their doctor.
Very rarely, some patients with Hashimoto’s disease may develop cancer cells in the thyroid due to development of cancer of the lymph cells (lymphoma). Again, patients should discuss any concerns they have with their doctor.
British Thyroid Foundation may be able to provide advice and support to patients and their families dealing with Hashimoto's disease.
Last reviewed: Apr 2020