Thyroid Hormones in the Human Body: A review

Abstract

Thyroid gland is an essential endocrine gland that is present in the human body. This review highlights the production, regulation and disease conditions of the thyroid hormones. The thyroid gland is controlled with the help of hypothalamus and the pituitary gland that is present in the brain. The production of thyroid hormones involves five main steps such synthesis of thyroglobulin (TG), iodide uptake, iodination of thyroglobulin, storage and release. The two important hormones produced by the thyroid gland are Thyroxine (T4) and Triiodothyronine(T3). These two hormones are iodine containing derivatives. Deficiency of iodine in the body results in the reduction of T3 and T4 production. Excess and deficiency of these two hormones result in the major diseases like Hyper and Hypothyroidism. The synthetic forms of Thyroxine(T4) and Triiodothyronine(T3) used in the Pharmaceutical field are Levothyroxine and Liothyronine. Women are most commonly prone to these thyroid diseases comparatively to men. Undiagnosed disease conditions may become fatal. Levothyroxine therapy is commonly used for thyroidism which is a similar synthetic thyroid hormone. Also natural thyroid hormones that are obtained from the dried thyroid glands of animals are available. Thyroid function test and the measurement of T3, T4 plasma level becomes essential for the identification and regular maintenance of thyroid hormones in the body and human well-being.