A lot of people confuse Hashimoto's as Hypothyroidism while it's not the case.

Hashimoto's disease is a disease, and hypothyroidism is a condition. Hypothyroidism is most commonly caused by Hashimoto's disease, but the two terms are not interchangeable. Here is more information to help understand the difference.
Hashimoto's disease, sometimes known as Hashimoto's thyroiditis, autoimmune thyroiditis, or chronic lymphocytic thyroiditis, is an autoimmune disease. In Hashimoto's, antibodies react against proteins in the thyroid gland, causing gradual destruction of the gland itself, and making the gland unable to produce the thyroid hormones the body needs.

Diagnosis

Hashimoto's disease is typically diagnosed by clinical examination that demonstrates one or more of the following findings:

  • Enlargement of the thyroid, known as a goiter
  • High levels of antibodies against thyroglobulin (TG) and thyroid peroxidase (TPO), detected via blood test
  • Fine needle aspiration of the thyroid (also known as a needle biopsy), which shows lymphocytes and macrophages
  • A radioactive uptake scan, which would show diffuse uptake in an enlarged thyroid gland
  • Ultrasound, which would show an enlarged thyroid gland