title: In congenital hypothyroidism, an initial L-thyroxine dose of 10-12 μg/kg/day is sufficient and sometimes excessive based on thyroid tests 1 month later.
abstract: BACKGROUND
  Current guidelines recommend an initial L-thyroxine (L-T4) dose of 10-15 μg/kg/day for the treatment of congenital hypothyroidism (CH). We analyzed our data for the treatment outcome at 1 month after we noted a frequent overtreatment even at the lower end of this dose range.
  
  
  METHODS
  A 3-year chart review of 55 patients with confirmed CH was performed. The patients were divided to three groups based on L-T4 dose: Group 1 (6-9.9 μg/kg), Group 2 (10-11.9 μg/kg), and Group 3 (12-15 μg/kg). Overtreatment was defined as T4>16 μg/dL/free T4>2.3 ng/dL±thyroid-stimulating hormone (TSH) <0.5 μIU/L and undertreatment was defined as TSH>6 μIU/L at 1 month.
  
  
  RESULTS
  At 1 month, 45.8%, 37.5%, and 16.6% in Group 1, 30%, 55%, and 15% in Group 2, and 0%, 75%, and 25% in Group 3 had target labs, overtreatment, and undertreatment, respectively.
  
  
  CONCLUSIONS
  An initial L-T4 dose of 10-11.9 μg/kg for TSH>100 μIU/L and 8-10 μg/kg for TSH<100 μIU/L at diagnosis met and often exceeded the target thyroid levels at 1 month. More frequent overtreatment was seen when >12 μg/kg was given.
authors: Children's National Medical Center, Washington, DC, USA. pvaidyan@cnmc.org
authors: Priya
authors: P
authors: Vaidyanathan
authors: Meenal
authors: M
authors: Pathak
authors: Paul B
authors: PB
authors: Kaplowitz
mesh_terms: D003409:Congenital Hypothyroidism / Q000097:blood / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use*
chemical_list: D013972:Thyrotropin; D013974:Thyroxine