Overview

Hashimoto's thyroiditis, also called chronic lymphocytic thyroiditis, is an autoimmune disorder in which the immune system targets the thyroid gland. Over time this process commonly reduces thyroid hormone production and leads to hypothyroidism. The condition is one of the most frequent causes of thyroid failure in regions with adequate iodine intake and is particularly more common in women and in middle age, although it can appear at any stage of life.

Causes and pathophysiology

The disorder arises when self-reactive immune cells and antibodies attack normal thyroid tissue. Key antibodies linked to the condition include anti-thyroid peroxidase and anti-thyroglobulin, which are markers used in clinical testing. The immune attack produces lymphocytic infiltration, formation of germinal centers, and characteristic changes in thyroid cells such as Hurthle cell transformation. Genetic susceptibility, environmental factors and other autoimmune conditions contribute to risk. For general context on autoimmune mechanisms see autoimmune disease, and for information about the role of antibodies see antibody-mediated processes.

Clinical features

  • Early stages may be asymptomatic or produce a painless, enlarged thyroid (goitre).
  • Many patients develop symptoms of underactive thyroid: fatigue, weight gain, cold intolerance, dry skin and slowed thinking.
  • Occasionally a transient thyrotoxic phase occurs when stored hormone is released.

Diagnosis and management

Diagnosis combines clinical assessment with laboratory tests. Elevated thyroid-stimulating hormone (TSH) with low free thyroid hormones points to hypothyroidism; antibody testing supports an autoimmune cause. Thyroid ultrasound can show a small, heterogeneous gland with reduced vascularity. Treatment focuses on hormone replacement—typically levothyroxine—for patients with symptomatic or overt hypothyroidism; monitoring is advised for those who are euthyroid. Referral and specialist follow-up are considered for uncertain cases, compressive goitre or suspicion of coexisting conditions.

History and notable facts

The condition was first described in 1912 by the Japanese physician Hakaru Hashimoto while working in Germany; early reports emphasized the chronic lymphocytic nature of the inflammation. For historical sources see Hashimoto's original description. Clinically important distinctions include its association with other autoimmune diseases and a rare increased risk of primary thyroid lymphoma. For more on thyroid anatomy and function see thyroid tissue.

Overall, Hashimoto's thyroiditis is a common, generally manageable cause of hypothyroidism that requires lifelong awareness and appropriate monitoring to maintain well-being.