Endocrine Abstracts

JOINT1257

The Wolff-Chaikoff effect refers to the temporary inhibition of thyroid peroxidase synthesis of thyroid hormone following excessive iodine exposure. Primary hypothyroidism has been reported in neonates, particularly very low birth-weight, following the use of iodine-based antiseptics and contrast agents. Thyroid function tests (TFTs) are not routinely monitored in this population. This case series describes 3 paediatric patients where severe hypothyroidism was (incidentally) detected following iodine exposure. Although typically transient, hypothyroidism can persist and evidence-based management protocols are lacking.

Cases: Three paediatric patients were referred to the Paediatric Endocrinology service for primary hypothyroidism following iodine exposure (cases summarised in table 1). All had prior TFTs, which were repeated post procedure for unrelated reasons. Cases 1 & 2 had iodine antiseptic exposure during laparotomy and bowel resection, while case 3 was exposed to an iodine-containing contrast agent (Omnipaque 240). Cases 1 & 3, with pre-exposure TSH elevation, were treated with thyroid hormone replacement due to persistent hypothyroidism.

Conclusion: Wolff-Chaikoff effect should be considered in paediatric cases following high-dose iodine exposure. Although congenital hypothyroidism’s neurodevelopmental impact is well-known, the effect of transient hypothyroidism is less understood, raising uncertainty about management. This series highlights two neonatal cases with pre-existing TFT derangements where hypothyroidism persisted beyond the typical period following iodine exposure. This underscores the need for careful iodine use and peri-exposure monitoring particularly in patients where thyroid abnormalities are already detected.