Hashimoto’s thyroiditis is a form of autoimmune thyroiditis that is often insidious and unrecognized, and is sometimes detected by chance during physical examination or when symptoms of hypothyroidism are present. Typical clinical manifestations: Mostly seen in middle-aged and elderly women, slow onset, long duration, diffuse enlargement of the thyroid gland, hard and tough, painless or light pressure pain, smooth surface, nodules may be present, local pressure and systemic symptoms are not obvious, occasional pharyngeal discomfort, normal or abnormal thyroid function. Hashimoto’s thyroiditis often takes a long time to develop from onset to abnormal thyroid function. It may present directly as hypothyroidism or it may first appear hyperfunctional but eventually progress to hypothyroidism. Atypical manifestations: In addition to the typical clinical manifestations described above, there are some specific manifestations of Hashimoto’s thyroiditis. An example is thyrotoxicosis. Hashimoto’s thyroiditis presents with thyrotoxicosis in two ways: Hashimoto’s hyperthyroidism and Hashimoto’s pseudohyperthyroidism (transient hyperthyroidism). Hashimoto hyperthyroidism refers to Hashimoto’s thyroiditis combined with hyperthyroidism, or Hashimoto’s combined with toxic diffuse goiter. The clinical features include hyperthyroidism with hyperthermia, sweating, hand tremors, weight loss, etc. The thyroid gland is enlarged, tough, and may have vascular murmurs; there may be infiltrative proptosis and anterior tibial mucinous edema. Hashimoto’s pseudohyperthyroidism is due to destruction of the thyroid gland and release of thyroid hormones. The symptoms are generally mild and the disease is easily controlled, with reduced iodine uptake by the thyroid gland and a rapid decline in thyroid function easily occurring after application of antithyroid drugs. Therefore, Hashimoto’s thyroiditis is difficult to detect early from the symptoms. For those at risk with a family history, regular checkups should be performed for early detection.