-On newborn screen.
-Refer to a pediatric endocrinologist.
-The patient will be treated with levothyroxine for life. Titration with goal TSH WNL.
“All infants with a low T4 concentration and a TSH concentration greater than 40 mU per L are considered to have congenital hypothyroidism and should have immediate confirmatory serum testing. Replacement levothyroxine (LT4) treatment should be initiated as soon as confirmatory samples have been taken, without waiting for the results (see Management and Treatment sections).” AFP2007
Further Reading
http://pediatrics.aappublications.org/content/117/6/2290
https://www.aafp.org/afp/2007/0801/p439.html