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Physiological TSH surge – neonate — RACP Paediatrics MCQ

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EasyEndocrinePhysiological TSH surge – neonateRACP Paediatrics

A neonate has screening TSH of 6 mU/L (just above the cutoff). Confirmatory free T4 is normal. TSH normalises on repeat at 2 weeks. The baby is well. What is the most likely explanation?

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Correct answer: B — Physiological TSH surge

A mildly elevated TSH in the first 24-48 hours that normalises on repeat testing is most likely the physiological TSH surge that occurs in normal neonates (peaking 30-60 minutes after birth and declining over 3-5 days). NBS samples taken very early (<24 hours) may capture this surge. If TSH is truly >20 or persists, further evaluation is needed.

Reference: RCH Melbourne – 2023 – Neonatal Thyroid CPG; RACP Paediatric Curriculum – Endocrine