Autoimmune thyroiditis: stages, forms and thyroid function

Autoimmune thyroiditis (Hashimoto's thyroiditis) is a chronic inflammation of the thyroid gland in which the immune system reacts against the body's own tissue. The disease begins slowly: months and even years may pass from the first changes to a decrease in hormone levels. Let us go through in order what stages and forms exist and how this relates to the function of the gland.

What autoimmune thyroiditis is

In AIT, the immune system produces antibodies against thyroid cells, gradually destroying its tissue. The result is a decrease in the production of thyroid hormones, a rise in TSH and the development of hypothyroidism. AIT occurs in 3–4% of the world's population, clinically manifest forms — about 1%; among patients there are 4–8 times more women than men, and the disease is most often detected in women over 60. The disease tends to run in families; half of relatives are found to have thyroid antibodies. It can be triggered by pregnancy and childbirth, iodine deficiency or excess, and deterioration of the environmental situation.

Stages of AIT: euthyroidism, subclinical and overt hypothyroidism

In the euthyroid phase and the phase of subclinical hypothyroidism there are usually no clinical manifestations. Only in isolated cases, already in euthyroidism, enlargement of the gland (goiter) comes to the fore, which rarely reaches significant degrees. When hypothyroidism develops, its symptoms begin to increase. To assess the function of the gland, the doctor uses:

• free T4 and TSH — basic tests of thyroid function;
• thyroid antibodies — confirm the autoimmune nature;
• complete blood count, prolactin, sodium, total cholesterol — may change in the disease;
• imaging studies and fine-needle biopsy are usually not needed for diagnosis.

Thyrotoxicosis in AIT: when the thyroid gland temporarily works excessively

Against the background of AIT, temporary hyperthyroidism (thyrotoxicosis) may develop — an increase in the production of thyroid hormones. This is a temporary condition.

Forms of AIT: hypertrophic and atrophic

A hypertrophic variant is distinguished (Hashimoto's thyroiditis proper): the thyroid gland is diffusely dense, function is not impaired or is moderately impaired — toward hypothyroidism or thyrotoxicosis. In the atrophic form, the gland is reduced at the time of examination, and hypothyroidism is noted. Postpartum thyroiditis is mentioned separately — in approximately 5–6% of women. Differential diagnosis is carried out with subacute thyroiditis, nodular goiter, thyroid cancer and other chronic thyroiditis; nodular goiter is mentioned precisely as a condition for differentiation; a separate "nodular form" of AIT is not distinguished.

How hypothyroidism manifests in AIT

Symptoms may be mild and unnoticeable, and develop gradually. Among the common ones: pronounced fatigue, chilliness, weight gain, constipation, difficulty concentrating, low mood, dry skin, dry hair or hair loss, hoarse voice, irregular or heavy menstruation. Enlargement of the neck or goiter is possible, and at a late stage — a small, shrunken gland. The main point: similar symptoms also occur in other conditions, so they are checked by a doctor.

How AIT is diagnosed and when to see a doctor

The doctor asks about symptoms, family history of thyroid and autoimmune diseases, recent pregnancy, and examines the neck. Blood tests for TSH and T4 are prescribed, and if necessary — additional tests and consultation with a specialist. You should see a doctor when symptoms of chronic thyroiditis or hypothyroidism appear. Some manifestations are emergencies: with infection, trauma or the use of certain medications, severe untreated hypothyroidism can lead to altered consciousness, coma and death.

AIT itself is not a reason to call an ambulance; 103 or 112 — if a person with severe untreated hypothyroidism develops altered consciousness or coma, especially against the background of infection, trauma or the use of opioids.

The material is for reference: it helps to understand the terms, but does not replace consultation with a doctor.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer