From the Guidelines
The diagnosis of autoimmune thyroiditis (Hashimoto's thyroiditis) is primarily based on elevated thyroid antibodies, particularly thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb), which are present in 90-95% of patients, as well as clinical and laboratory findings such as hypothyroidism and a firm, diffusely enlarged thyroid gland. The diagnostic criteria for autoimmune thyroiditis include:
- Elevated thyroid antibodies, specifically TPOAb and TgAb, which are the most specific diagnostic tools, reflecting the underlying autoimmune process where the immune system attacks thyroid tissue 1
- Thyroid function tests showing hypothyroidism (elevated TSH and low free T4), though patients may initially be euthyroid or even transiently hyperthyroid
- Physical examination findings of a firm, diffusely enlarged thyroid gland that may be painless or mildly tender
- Ultrasound characteristics of a heterogeneous, hypoechoic thyroid with increased vascularity
- Family history of thyroid or other autoimmune disorders, which strengthens the diagnosis
- Presence of other autoimmune conditions such as type 1 diabetes, celiac disease, or vitiligo, which also supports the diagnosis It is essential to note that the serum TSH test is the primary screening test for thyroid dysfunction, and multiple tests should be done over a 3- to 6-month interval to confirm or rule out abnormal findings, as stated in the USPSTF recommendation statement 1. The principal treatment for hypothyroidism, a common consequence of autoimmune thyroiditis, is oral T4 monotherapy (levothyroxine sodium) 1. In clinical practice, the diagnosis of autoimmune thyroiditis relies on a combination of these diagnostic criteria, with antibody testing being the most specific tool, and treatment is focused on managing hypothyroidism and other related symptoms.
From the Research
Diagnostic Criteria for Autoimmune Thyroiditis (Hashimoto's Thyroiditis)
The diagnostic criteria for autoimmune thyroiditis (Hashimoto's thyroiditis) include:
- Presence of antibodies against thyroid-specific antigens, primarily anti-thyroid peroxidase antibodies (TPOAb) and anti-thyroglobulin antibodies (TgAb) 2, 3, 4, 5
- Sonographically proven reduced echogenicity of the thyroid parenchyma 3, 5
- Clinical signs and symptoms of hypothyroidism, such as fatigue, bradycardia, constipation, and cold intolerance 3, 6
- Elevated thyroid-stimulating hormone (TSH) levels, with or without reduced serum free thyroxine (fT4) and triiodothyronine (fT3) levels 3, 6
Laboratory Findings
Laboratory findings that support the diagnosis of autoimmune thyroiditis include:
- Elevated TPOAb and TgAb levels 2, 3, 4, 5
- Elevated TSH levels, with or without reduced fT4 and fT3 levels 3, 6
- Presence of other autoantibodies, such as anti-thyroid receptor antibodies (TRAb) 2
Imaging Findings
Imaging findings that support the diagnosis of autoimmune thyroiditis include:
- Reduced echogenicity of the thyroid parenchyma on ultrasound 3, 5
- Thyroid gland enlargement or nodular goiter 6
Clinical Considerations
Clinical considerations that support the diagnosis of autoimmune thyroiditis include: