TY  - CHAP
M1  - Book, Section
TI  - Chapter 59. Thyroid Disorders
A1  - Blake, Elizabeth W.
A2  - Sutton, S. Scott
PY  - 2011
T2  - McGraw-Hill's NAPLEX® Review Guide
AB  - The  thyroid  gland,  located  in  the  front  of  the  neck,  has  two  main  functions—to  secrete  thyroid  hormones  and  to  secrete  calcitonin.1  The  thyroid  gland  operates  via  a  negative  feedback  mechanism  to  synthesize  thyroid  hormones.2  The  hypothalamus  produces  thyrotropin-releasing  hormone  (TRH)  which  then  stimulates  the  pituitary  to  release  thyroid-stimulating  hormone  (TSH).  TSH,  also  known  as  thyrotropin,  then  stimulates  the  synthesis  and  release  of  thyroid  hormones  from  the  thyroid  gland.  Formation  of  thyroid  hormones  requires  iodination  of  tyrosine  residues  by  thyroid  peroxidase  to  produce  monoiodinated  and  diiodinated  residues  that  couple  to  form  triiodothyronine  (T3)  and  levothyroxine  (T4).3  Circulating  levels  of  these  hormones  regulate  the  amount  of  TSH  secreted.  While  the  thyroid  gland  is  responsible  for  the  production  of  all  T4,  only  20%  of  T3  is  secreted  by  the  thyroid.  Peripheral  conversion  of  T4  to  T3  forms  the  majority  of  T3.  T3  is  more  potent,  less  bound  to  plasma  proteins,  and  has  a  greater  affinity  for  the  thyroid  receptor.2,3  Thyroid  hormones  affect  multiple  organ  systems  throughout  the  body  (Table  59-1).1-4  Alterations  in  these  hormone  concentrations  along  with  changes  in  TSH  will  lead  to  hyper-  or  hypothyroidism.2  (Table  59-2)  
SN  - 
PB  - The McGraw-Hill Companies
CY  - New York, NY
Y2  - 2024/04/19
UR  - accesspharmacy.mhmedical.com/content.aspx?aid=7255724
ER  -