Chronic lymphocytic thyroiditis

by Jason Wasserman MD PhD FRCPC
February 13, 2023

What is chronic lymphocytic thyroiditis?

Chronic lymphocytic thyroiditis, also known as Hashimoto’s thyroiditis, is an autoimmune disorder that affects the thyroid gland. In this condition, cells from the immune system attack the thyroid gland, causing inflammation and damage to the cells in the gland. As a result, the thyroid gland gradually loses its ability to produce thyroid hormones, which regulate metabolism and play a crucial role in overall health.

Thyroid gland

What are the symptoms of chronic lymphocytic thyroiditis?

Common symptoms of chronic lymphocytic thyroiditis include fatigue, weight gain, cold intolerance, depression, and muscle weakness. These symptoms develop as a consequence of hypothyroidism (low levels of thyroid hormones in the blood). However, many people with the condition may not experience any symptoms for years, and the condition may be discovered incidentally during routine health check-ups.

What causes chronic lymphocytic thyroiditis?

Chronic lymphocytic thyroiditis is an autoimmune disorder. It is caused by autoantibodies (antibodies that target tissues that are normally found in the body) that stick to cells in the thyroid gland. These autoantibodies stimulate cells in the immune system to attack the thyroid gland. At present, doctors do not know exactly why some people develop the autoantibodies that lead to this condition. However, it is believed that a combination of genetic and environmental factors increases the risk of developing chronic lymphocytic thyroiditis.

Factors that may increase the risk of developing chronic lymphocytic thyroiditis include:
  • Family history of autoimmune disorders: People with a family history of autoimmune disorders are more likely to develop chronic lymphocytic thyroiditis.
  • Gender: Women are more likely to develop chronic lymphocytic thyroiditis than men.
  • Age: The risk of developing chronic lymphocytic thyroiditis increases with age, particularly in women over the age of 60.
  • Radiation exposure: Exposure to radiation, such as from medical procedures or environmental sources, can increase the risk of developing chronic lymphocytic thyroiditis.
  • Other autoimmune disorders: People with other autoimmune disorders, such as type 1 diabetes or rheumatoid arthritis, are at a higher risk of developing chronic lymphocytic thyroiditis.

How is chronic lymphocytic thyroiditis diagnosed?

Chronic lymphocytic thyroiditis is typically diagnosed through a combination of blood tests that measure thyroid hormone levels and antibodies associated with autoimmune disorders and examination of tissue from the thyroid gland under the microscope.

What does chronic lymphocytic thyroiditis look like under the microscope?

When examined under the microscope, immune cells such as lymphocytes and plasma cells will be seen throughout the thyroid gland. In more advanced disease, the immune cells may form round structures called lymphoid follicles. Lymphoid follicles are typically seen in immune organs called lymph nodes and their presence in the thyroid gland is a sign that the disease has been ongoing for a long time. The normal thyroid cells may show a variety of reactive changes including oncocytic metaplasia and cytologic atypia.

Chronic lymphocytic thyroiditis
This image shows an example of chronic lymphocytic thyroiditis examined under the microscope. The round structure in the center is a lymphoid follicle.
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