RT Book, Section
A1 Brent, Gregory A.
A1 Koenig, Ronald J.
A2 Brunton, Laurence L.
A2 Chabner, Bruce A.
A2 Knollmann, Björn C.
SR Print(0)
ID 1127869305
T1 Thyroid and Anti-Thyroid Drugs
T2 Goodman & Gilman's: The Pharmacological Basis of Therapeutics, 12e
YR 2015
FD 2015
PB McGraw-Hill Education
PP New York, NY
SN 9780071624428
LK accessmedicine.mhmedical.com/content.aspx?aid=1127869305
RD 2022/01/29
AB Thyroid  hormone  is  essential  for  normal  development,  especially  of  the  central  nervous  system  (CNS).  In  the  adult,  thyroid  hormone  maintains  metabolic  homeostasis  and  influences  the  function  of  virtually  all  organ  systems.  Thyroid  hormone  contains  iodine  that  must  be  supplied  by  nutritional  intake.  The  thyroid  gland  contains  large  stores  of  thyroid  hormone  in  the  form  of  thyroglobulin.  These  stores  maintain  systemic  concentrations  of  thyroid  hormone  despite  variations  in  iodine  availability  and  nutritional  intake.  The  thyroidal  secretion  is  predominantly  the  prohormone  thyroxine,  which  is  converted  in  the  liver  and  other  tissues  to  the  active  form,  triiodothyronine.  Local  activation  of  thyroxine  also  occurs  in  target  tissues  (e.g.,  brain  and  pituitary)  and  is  increasingly  recognized  as  an  important  regulatory  step  in  thyroid  hormone  action.  Serum  concentrations  of  thyroid  hormones  are  precisely  regulated  by  the  pituitary  hormone,  thyrotropin  (TSH),  in  a  classic  negative-feedback  system.  The  predominant  actions  of  thyroid  hormone  are  mediated  through  binding  to  nuclear  thyroid  hormone  receptors  (TRs)  and  modulating  transcription  of  specific  genes.  Thyroid  hormones  share  a  common  mechanism  of  action  with  steroid  and  steroid-like  hormones,  such  as  vitamin  D  and  the  retinoids,  whose  receptors  are  members  of  a  superfamily  of  nuclear  receptors  (Chapter  3).  Although  the  predominant  actions  of  thyroid  hormone  are  nuclear,  actions  of  thyroid  hormone  outside  the  nucleus  have  been  reported.