Hashimoto’s disease is a condition in which the body’s immune system starts to attack the thyroid gland. The thyroid gland may be damaged by inflammation caused by antibodies attacking the gland and this may result in some swelling of the thyroid gland. It also stops the thyroid gland working well and causes hypothyroidism (low levels of thyroid hormones).
Hashimoto’s disease is caused by inflammation of the thyroid gland, which is often called thyroiditis. The inflammation results from the body producing proteins called antibodies that attack cells within the thyroid gland. Antibodies usually recognise and remove foreign substances, such as bacteria or viruses, but occasionally they recognise part of our body as 'foreign' and mount an attack against these parts of the body, such as the thyroid gland. It is not known why this happens, but we do know there is a tendency for this type of thyroid disease (termed 'autoimmune') to run in families.
Hashimoto’s disease can develop gradually over a long period of time. Symptoms are not always specific to the disease and can vary among different individuals. The symptoms of Hashimoto’s disease are usually those of a swollen thyroid gland (goitre) and hypothyroidism. Rarely, people with Hashimoto’s disease can have symptoms of an overactive thyroid (hyperthyroidism) in the early stages of the disease. Some patients may have blood tests that show a mildly low thryoid hormone levels called subclinical hypothyroidism. This may not need treatment if they have no symptoms.
The thyroid gland can be mildly swollen and rubbery to the touch, but not usually tender. If the condition is left untreated, signs of hypothyroidism develop. Usually the swelling of the thyroid gland is noticed well before symptoms develop.
Patients may feel tired and lethargic. Bowel movements slow down causing constipation. There may be drying of the skin and hair, and hair changes (such as thinning or loss of hair). There may be painful and stiff muscles, difficulty in tolerating cold weather, weight gain and hoarseness of the voice. Women may notice a change in their periods, usually with them becoming heavier.
Hashimoto’s disease causing hypothyroidism is found in just above 2% of the population, although its occurrence increases with age. It is more common than hyperthyroidism (an overactive thyroid gland) and women are between eight and ten times more likely to be affected than men. Hashimoto’s disease is also the main cause of thyroid problems in children and the elderly.
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.
There are a number of different ways that Hashimoto’s disease can be diagnosed. Blood tests for the thyroid function will show any abnormality. These blood tests will measure the level of thyroid hormones (thyroxine and triiodothyronine) and thyroid stimulating hormone. The level of thyroid stimulating hormone 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 be detected in blood tests, although not every person with antibodies will develop a serious thyroid disease. These tests can all be carried out as an outpatient.
A scan of the thyroid gland is rarely needed. If there is uneven swelling of the thyroid gland, the doctor may request a scan and may do a small biopsy with a needle (fine needle aspiration) to look at the cells.
The doctor may also request blood tests to ensure that no other autoimmune condition is present or developing.
Treatment is carried out as an outpatient and depends on how well the thyroid gland is working.
An overactive gland usually settles down by itself and hypothyroidism develops with time.
Hypothyroidism should be treated with levothyroxine tablets as a replacement for thyroid hormone. Blood tests to measure thyroid stimulating hormone will be needed to check that the dose is correct, 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.
If the thyroxine replacement is monitored adequately and 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.
Last reviewed: Mar 2018