Neonatal thyroid enlargement associated with propylthiouracil therapy of Graves' disease during pregnancy: A problem revisited

roid enlargement may be caused by TSH stimulation of the fetal thyroid gland (secondary to PTU-induced fetal hypothyroidism) or secondary to TSIG stimulation. Thyroid enlargement can be severe enough to cause respiratory compromise and should always be considered in the differential diagnosis of a neonatal neck mass.