Neonatal Endocrinology

Question 1

Transient Hypothyroxinemia of Prematurity (THOP)

Answer 1

Low thyroid hormone levels in preterm infants (esp <34 weeks) due to:

(1) Interruption of placental transfer of maternal thyroid hormone that happens during pregnancy

(2) Immaturity of HPT axis, lack of response to TSH surge at time of birth

Question 2

TSH and thyroid hormone levels can be affected by which medications?

Answer 2

Dopamine, dexamethasone, methylxanthines (caffeine), etc.

Can also be affected by illness and stress