Human thyroid-stimulating hormone (hTSH) is a glycoprotein of about 30 KDa, secreted by the anterior pituitary gland. It consists of 2 non-covalently bound subunits (α and β).
The main function of hTSH is to determine
Human thyroid-stimulating hormone (hTSH) is a glycoprotein of about 30 KDa, secreted by the anterior pituitary gland. It consists of 2 non-covalently bound subunits (α and β).
The main function of hTSH is to determine the thyroid development, stimulating and regulating the secretion of metabolically active hormones: Thyroxine (T4) and Triiodothyronine (T3). The synthesis of hTSH is controlled by the hypothalamic regulatory hormone (TRH) and by the concentration of the circulating thyroid hormone, through negative feedback.
The hTSH serum level is considered one of the best indicators of the thyroid functionality. The balance, present in normal conditions, among the circulating thyronines level, TRH and hTSH can be altered in several cases of thyroid pathology. High levels of hTSH are found in case of: primary hypothyroidism (from thyroid alteration – low concentration of circulating thyroid hormones); secondary hyperthyroidism (from pituitary alteration – presence of pituitary tumor). Low levels of hTSH are found in case of: primary hyperthyroidism (high concentration of T3 and T4); secondary or tertiary hyperthyroidism, due to rare hypothalamic or pituitary abnormalities.
