Case study: Baby A, a boy was delivered at 33 weeks gestation (birth weight 1.545 kg, 9th centile) by emergency caesarean section following maternal preeclampsia. He did not require any resuscitation at birth. He is the second baby of non-consanguineous Asian parents with no family history to note. Both parents are healthy and there was no history of maternal medication use. Baby A experienced respiratory distress syndrome and suspected sepsis. He developed a heart murmur, confirmed by echocardiography to be a ventricular septal defect and atrial septal defect. After initial intravenous fluids he was established on expressed breast milk by nasogastric tube. As he was failing to thrive, Baby As feed was switched to high-calorie formula and there was a brief period where his weight seemed to be improving. Around this time he also developed symptoms of gastroesophageal reflux disease and was commenced on Ranitidine and Gaviscon. His vomiting and weight gain failed to improve. Furthermore he required continued nasogastric feeding, out of keeping for his prematurity. Investigations included a metabolic screen. Surprisingly, in-spite of a normal newborn screen, his thyroid-stimulating hormone (TSH) was extremely high at 340 mU/l with free-T4 at 4.0pmol/L. An urgent radioisotope scan revealed a bulky thyroid. We also looked for rarer causes of hypothyroidism including iodine exposure and initial urinary iodine/creatinine ratio was high at 2361 nmol/mmol (50360 nmol/mmol). Repeat results as well as maternal urinary iodine are pending. We are continuing to investigate how this baby has been exposed to iodine. Levothyroxine was commenced at 25 μg and adjusted as shown in the table below (Table 1).
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Conclusion: This case highlights the importance of further investigations into hypothyroidism when initial screening results are normal, especially to exclude exposure of the baby to excess iodine.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology