Hashimoto's thyroiditis (autoimmune thyroiditis)

Hashimoto's affects the thyroid, a small gland in the neck. The immune system is thought to gradually inflame and damage thyroid tissue, mediated by antibodies against thyroid peroxidase and thyroglobulin along with T-cell activity that drives progressive fibrosis of the gland. Over time this can lower thyroid hormone output and lead to an underactive thyroid (hypothyroidism). It often involves a goiter, an enlarged thyroid.

Hashimoto's is the most common autoimmune thyroid condition and the most common cause of hypothyroidism in regions where iodine intake is adequate. A 2022 meta-analysis estimated the condition affects roughly 7.5 percent of adults worldwide, though reported rates vary widely by region and screening method. It is markedly more common in women, with a female-to-male ratio estimated between 7:1 and 10:1, and most often diagnosed between ages 45 and 55.

Common signs

fatigue, feeling cold, weight gain, dry skin, hair thinning, constipation, low mood, brain fog, and a puffy face. Symptoms often build slowly.

This is a plain-language summary for orientation, not a diagnosis. Mechanisms are described as current understanding, not settled fact. Work with your own clinician for your care.