Acquired hypothyroidism

Synonyms in the broadest sense

Acquired hypothyroidism, Hashimoto’s thyroiditis, autoimmune disease, thyroiditis, postoperative hypothyroidism, primary, secondary, tertiary hypothyroidism, latent hypothyroidism, myxedema

Definition

Hypothyroidism occurs when the thyroid gland produces insufficient amounts of thyroid hormones (T3 and T4). The consequence is that the hormone action on the target organs is absent. Overall, the thyroid hormones increase the overall metabolism and promote development and growth. In addition, the thyroid hormones play an important role in controlling the calcium and phosphate balance. Furthermore, they stimulate protein production (=protein biosynthesis) and the formation of the sugar storage substance glycogen.

Introduction

A distinction is made between primary, secondary and tertiary forms of hypothyroidism. Primary hypothyroidism Secondary hypothyroidism This form is very rare and occurs when the pituitary gland (hypophysis) is no longer able to produce TSH and thus the thyroid hormone production in the periphery is not stimulated. Tertiary hypothyroidism This form of hypothyroidism is also rare.

It is caused by the lack of TRH production in the central nervous system, so that the regulatory cycle of thyroid hormones no longer functions. Latent hypothyroidism This form of hypothyroidism does not cause any symptoms in the patient, which is why it is also referred to as a subclinical form (= without any detectable symptoms in the patient). It is diagnosed by the hormone determination in the blood: The concentrations of T3 and T4 are normal, the value for TSH is highly normal to elevated.

• The hypofunction of the thyroid gland occurs as a consequence of an autoimmune disease, an inflammation of the thyroid gland (=Hashimoto’s thyroiditis). In this case, thyroid cells die and the production of hormones is limited.
• Hypothyroidism caused by medical measures also belongs to the primary form of the disease. After removal of the thyroid gland (=strumectomy), after radioiodine therapy or due to drug treatment with e.g. lithium or thyrostatics, the hormone production of the thyroid gland may be restricted.