Summary Hemiagenesis of the thyroid gland (THA) represents a rare congenital anomaly. It is characterized by the absence of one thyroid lobe, and sometimes the isthmus as well. It can occur with all kinds of other thyroid pathologies that may be present in the remaining thyroid lobe. A case of a 21-year-old male patient is presented; he sought a thyroid consultation because of hair loss, fatigue, and problems concentrating, thus raising the suspicion of hypothyroidism. Thyroid function was normal, but sonography of the thyroid gland revealed THA of the left lobe and the isthmus. The current knowledge concerning the genesis and the clinical consequences of THA are discussed based on the current literature.

SummaryHashimoto’s thyroiditis (HT), also known as chronic lymphocytic thyroiditis, is a frequent disorder of the thyroid gland caused by autoimmune-trigged lymphocytic infiltration and destruction of the thyroid gland. With the progressive destruction of the organ, the thyroid gland shrinks in size, thus commonly leading to hypothyroidism. Therapy of HT is mainly focused on managing the thyroid dysfunction by oral substitution of L‑thyroxine. However, patients with HT often complain about a broad spectrum of symptoms, with some of them hardly explained by HT itself. Several other disorders are known to be associated with HT. The etiology of HT seems to be multifactorial, including environmental influences such as iodine supply, infections, and stress as triggers of immune modulation. In addition, also a genetic background based on changes of the human leukocyte antigen (HLA) status seems to be evident. The paper will provide an overview of diseases related to HT, including their correlation to certain HLA patterns. This presentation should give a broader view on HT-related disorders and facilitate detailed examination and management of patients with HT.