Pregnancy and PTU

Abstract

In this issue of the Journal Cheron et al. report that modest doses of propylthiouracil (PTU) ingested by mothers being treated for Graves' disease significantly reduce serum thyroxine in newborn infants.This finding is an important extension of previous observations. It has long been known that PTU crosses the placenta and is active against the fetal thyroid. Furthermore, many studies have shown that maternal thyroxine (T₄) and triiodothyronine (T₃) are in effect barred from reaching the fetal circulation except at extremely high maternal serum concentrations.¹ Thus, overt fetal hypothyroidism and goiter result from large doses of . . .