From: The ratio of serum free triiodothyronine to free thyroxine in children: a retrospective database survey of healthy short individuals and patients with severe thyroid hypoplasia or central hypothyroidism
Congenital thyroid hypoplasiaa
Central hypothyroidisma
FT3/FT4 ratio
↓↓
↓
FT3
FT4
↑↑
→