part of part of has part has part characteristic of inheres in has role has modifier chemical entity thyroid hormone Abnormality of thyroid physiology Abnormal circulating hormone concentration Abnormal circulating thyroid hormone concentration 2017-09-21T01:56:23Z Abnormal thyroid hormone level Any deviation from the normal range of the hormones produced by the thyroid gland. Thyroid hormones (TH) are involved in the regulation of metabolism, proliferation, and growth of most tissues. Serum TH levels are tightly controlled by the hypothalamic, pituitary, and thyroid (HPT) axis to deliver appropriate amounts of TH to target tissues. The two major THs (T3 and T4) are iodothyrosines synthesized by the thyroid gland under the control of thyrotropin/thyroid stimulating hormone (TSH), a glycoprotein heterodimer that is produced by the pituitary gland. TSH, in turn, is regulated by thyrotropin releasing hormone (TRH), a tripeptide generated by the hypothalamus that is released into its own portal system to reach the pituitary. Both the production of TRH and TSH are under negative feedback control determined by the circulating free TH concentrations. amount abnormal blood