Hashimoto

Hashimoto's thyroiditis, commonly called Hashimoto's disease, is an autoimmune thyroid disorder described by Hakaru Hashimoto in 1912. It is the most common cause of hypothyroidism in regions with adequate iodine. The disease involves immune-mediated destruction of thyroid tissue by autoreactive T cells and autoantibodies against thyroid antigens such as thyroid peroxidase (TPO) and thyroglobulin. The condition typically follows a chronic course, with gradual gland destruction.

Many patients present with a painless enlarged thyroid (goiter). Symptoms reflect reduced thyroid hormone levels and may include fatigue, weight gain, cold intolerance, constipation, dry skin, and hair loss. Some people experience a transient thyrotoxic phase early in the disease (Hashitoxicosis). Autoimmune associations are common, and other autoimmune diseases may co-occur.

Diagnosis is based on thyroid function tests showing elevated TSH and low free thyroxine (FT4), and serology positive for thyroid autoantibodies (TPOAb, TgAb). Neck ultrasound may show a heterogeneous, hypoechoic gland with increased vascularity. Fine-needle aspiration is used when cancer is suspected or to evaluate suspicious nodules.

Most patients require thyroid hormone replacement with levothyroxine to normalize TSH. The dose is adjusted to symptoms and laboratory tests, with special attention during pregnancy. Regular monitoring is recommended. Prognosis is generally good with treatment; some individuals may remain euthyroid or progress to lifelong hypothyroidism. Hashimoto's autoimmune thyroiditis can be associated with other autoimmune conditions.