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PTU-Induced Neonatal Hypothyroidism — RACP Paediatrics MCQ

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HardEndocrinologyPTU-Induced Neonatal HypothyroidismRACP Paediatrics

A neonate has a goitre and is hypothyroid (elevated TSH, low fT4). His mother was taking propylthiouracil during pregnancy for Graves disease. What is the cause?

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Correct answer: E — Transplacental passage of PTU causing fetal/neonatal hypothyroidism

Antithyroid drugs (PTU, carbimazole/methimazole) cross the placenta and can cause fetal/neonatal hypothyroidism and goitre. The effect is transient, resolving as maternal drug is cleared. Neonatal thyroid function should be monitored. Levothyroxine replacement may be needed temporarily.

Reference: RCH Melbourne – 2024 – Clinical Practice Guidelines: Neonatal Thyroid Disorders