Diagnostic Criteria for Serum Thyroid Hormones in Congenital Hypothyroidism

Diagnosis	Diagnostic Criteria
Primary Hypothyroidism	TSH>9 mIU/L; FT₄<0.6 ng/dL
Primary Subclinical Hypothyroidism	TSH>9 mIU/L; FT₄ normal (0.9-0.23 ng/dL)
TBG Deficiency	TSH normal (<9 mIU/L); FT₄ normal (0.9-0.23 ng/dL); TT₄ decreased (<5μg/dL); T3RUR>45%
Central Hypothyroidism	TSH<9 mIU/L or normal; FT₄ decreased (<0.6ng/dL); TT₄ decreased (<5μg/dL)

T₄: 1μg/dL*12.87=1nmol/L;

FT₄: 1ng/dL*12.87=1pmol/L