title: Definitive diagnosis in children with congenital hypothyroidism.
abstract: OBJECTIVE
  To investigate the definitive diagnosis and underlying causes of congenital hypothyroidism (CH) in eligible children through the use of a standardized protocol.
  
  
  METHODS
  Children > or =3 years of age with CH without an identified permanent cause underwent a diagnostic algorithm. Eligible subjects had an anatomically normal thyroid or had not undergone imaging studies. After thyroxine was discontinued for 4 weeks, thyroid function tests and a thyroid ultrasound were obtained. An abnormal ultrasound was followed by a (99m)Tc thyroid scan. A perchlorate washout test was performed in subjects with a normal ultrasound but abnormal thyroid function tests. Children with normal results were followed for 1 year.
  
  
  RESULTS
  Of 33 children, 17 were boys. Nine (27%) had an absent or ectopic thyroid, 12 (36%) had dyshormonogenesis, and 12 (36%) had transient CH. Average thyroxine dose before medication discontinuation was 2.9 +/- 0.83 microg/kg in permanent cases versus 2.0 +/- 0.53 microg/kg in transient (P <.002). No complications from discontinuation of thyroxine occurred.
  
  
  CONCLUSIONS
  A significant percentage of children with CH have a transient requirement for thyroid hormone. A standardized protocol with thyroid ultrasonography is a safe and sensitive approach to a trial off of thyroxine in select patients.
authors.affiliation: Department of Pediatrics, James Whitcomb Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA. eeugster@iupui.edu
authors.forename: Erica A
authors.initials: EA
authors.lastname: Eugster
authors.forename: Debbie
authors.initials: D
authors.lastname: LeMay
authors.forename: J Michael
authors.initials: JM
authors.lastname: Zerin
authors.forename: Ora H
authors.initials: OH
authors.lastname: Pescovitz
mesh_terms: D000465:Algorithms; D002675:Child, Preschool; D003409:Congenital Hypothyroidism; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000175:diagnosis*; D008297:Male; D012680:Sensitivity and Specificity; D013961:Thyroid Gland / Q000000981:diagnostic imaging; D013974:Thyroxine / Q000008:administration & dosage; D014463:Ultrasonography
chemical_list: D013974:Thyroxine