evidence: The etiology of Hashimoto disease is very poorly understood. Most patients develop antibodies to a variety of thyroid antigens, the most common of which is anti-thyroid peroxidase (anti-TPO). Many also form antithyroglobulin (anti-Tg) and TSH receptor-blocking antibodies (TBII). These antibodies attack the thyroid tissue, eventually leading to inadequate production of thyroid hormone. There is a small subset of the population, no more than 10% to 15%, with clinically evident disease that are serum antibody-negative. Positive TPO antibodies presage the clinical syndrome.[3][4] [...] Hashimoto thyroiditis is a lifelong disorder with no cure; thus, it is best managed by an interprofessional team that includes an endocrinologist, primary care provider, and an internist. The key is to follow up on the levels of thyroid hormone. Empirically prescribing one standard dose of levothyroxine may lead to hormone toxicity in some people. In addition, some patients may develop lymphoma, and thus a regular examination of the neck area is highly recommended.