The most characteristic manifestations are pain and pressure in the thyroid gland, often radiating to the submandibular area, behind the ear or neck, and increasing when chewing and swallowing. The extent of thyroid lesions varies, starting in one lobe and later expanding or shifting to another lobe, or remaining confined to one lobe. The lesion is enlarged and hard, with significant pressure pain. When the lesion is extensive, there is a transient release of thyroid hormones and non-hormonal iodinated proteins into the bloodstream, resulting in the usual manifestations of hyperthyroidism in addition to the usual manifestations of infection. In the later stage, when the thyroid hormones in the thyroid vesicles are depleted due to the infection and before the parenchymal cells of the thyroid gland are repaired, the serum thyroid hormone concentration may drop to hypothyroidism level, and the clinical manifestations of hypothyroidism may also be present.