What are the key clinical features and laboratory findings that support a diagnosis of Hashimoto's Thyroiditis in adults?

Key clinical features supporting a diagnosis of Hashimoto's thyroiditis in adults include symptoms of hypothyroidism such as fatigue, weight gain, cold intolerance, constipation, dry skin, and depression, although symptoms may be subtle or absent initially ¹. Physical examination may reveal a diffusely enlarged, firm, and non-tender thyroid gland (goitre) ¹. There may also be a history of other autoimmune diseases or family history of thyroid autoimmunity (Ragusa et al., 2019).

Laboratory findings that support the diagnosis include elevated thyroid-stimulating hormone (TSH) levels with low or normal free thyroxine (FT4), consistent with hypothyroidism or subclinical hypothyroidism ¹. The hallmark laboratory feature is the presence of thyroid peroxidase antibodies (TPOAbs), which are elevated in most cases and indicate autoimmune thyroid destruction ¹. Testing for TPOAbs is recommended in adults with elevated TSH to confirm autoimmune thyroiditis ¹. Thyroglobulin antibodies may also be present but are less specific (Ragusa et al., 2019).

Ultrasound imaging, while not diagnostic alone, typically shows a diffusely hypoechoic and heterogeneous thyroid gland with reduced vascularity, supporting the diagnosis in conjunction with clinical and serological findings ¹.

In summary, the diagnosis of Hashimoto's thyroiditis in adults is supported by clinical features of hypothyroidism or goitre, elevated TSH, positive TPOAbs, and characteristic ultrasound findings ¹; these are consistent with the autoimmune pathogenesis described in recent literature (Ragusa et al., 2019).