Neonatal Iodine-Induced Hypothyroidism After Cardiac Arteriography

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 596-623-Case Reports: Pediatric Endocrinology & Metabolism
Clinical
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-622
Vidhu Thaker*1, Bat-Sheva Levine1, Angela M Leung2 and Lewis E Braverman2
1Boston Children's Hospital, Boston, MA, 2Boston University School of Medicine, Boston, MA
Introduction: Thyroid hormone plays a crucial role in infant neurodevelopment. Excess iodine exposure may transiently inhibit thyroid hormone synthesis (the acute Wolff-Chaikoff effect), but escape from the acute Wolff-Chaikoff effect in the developing neonate may be impaired. We present 3 neonates with CHD (congenital heart disease) and normal initial newborn screening (NBS) TSH levels who developed iodine-induced hypothyroidism following iodinated contrast administration for cardiac arteriography.

Clinical cases:

Case 1: A full-term infant with CHD who had a normal NBS TSH received 6.2 mL/kg of Optiray 350 (6,900 mg iodine) for cardiac catheterization on day 3 of life. Subsequent serum thyroid function tests: TSH 18.1 mIU/L (1.7-9.1), TT4 4.1 µg/dL (>5) [day 12]; TSH 63.7 mIU/L, TT4 3.2 µg/dL [day 20]; TSH 175 mIU/L, FT4 0.3 ng/dL (0.9-2.3) [day 25]. Day 25 blood spot filter paper iodine was elevated to 0.020 µg (<0.01) and spot urine iodine to 835 µg/L (150-220). Thyroid hormone replacement (12 µg/kg/d) was initiated on day 26; the infant continues to receive thyroid replacement therapy.

Case 2: A full-term infant with CHD who had a normal NBS TSH underwent cardiac catheterizations on days 2 and 3 of life, with a cumulative Optiray 350 dose of 9.7 mL/kg (10,900 mg iodine). On day 13, TSH was 42.7 mIU/L and FT4 was 1.44 ng/dL. Serum iodine was markedly elevated to 888 ng/mL (40-92), spot filter paper blood iodine to 0.085 µg (<0.01), and spot urine iodine to 2,664 µg/L (150-220). Thyroid replacement therapy (12 µg/kg/d) was initiated and thyroid function normalized by day 23, after which the infant began to wean off therapy.

Case 3: A full-term infant with CHD who had a normal NBS TSH underwent cardiac catheterization with 5.6 mL/kg of Optiray 350 (5,500 mg iodine) on day 17 of life. Serum TSH was 30.1 mIU/L, TT4 12.3 µg/dL, and spot urine iodine 13,827 µg/L (day 31). Thyroid function normalized on day 45 without treatment.

All 3 infants had left-sided structural heart disease. There was no history of maternal thyroid dysfunction, excess iodine ingestion, or exposure to iodine-containing antiseptics.

Conclusion: Iodine excess from iodinated contrast use during cardiac catheterization can result in hypothyroidism in neonates with CHD. Thyroid function should be routinely monitored in infants undergoing such procedures during this critical period of early development.

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1. Rhee CM, Bhan I, Alexander EK, et al. Association between iodinated contrast media exposure and incident hyperthyroidism and hypothyroidism. Arch Intern Med 2012; 172(2):153-159. 2. Linder N, Sela B, German, B,  et al. Iodine and hypothyroidism in neonates with congenital heart disease. Arch Dis Child Fetal Neonatal Ed 1997; 77:F239-F240. 3. Delange F, Heidemann P, Bourdoux P, et al. Regional variations of iodine nutrition and thyroid function during the neonatal period in Europe. Biol Neonate 1986; 49(6):322-30. 4. Delange F, Dalhem A, Bourdoux P, et al. Increased risk of primary hypothyroidism in preterm infants. J Pediatr 1984; 105(3):462-9.

Nothing to Disclose: VT, BSL, AML, LEB

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: Acknowledgements: 5K23HD068552-02 (Leung). We wish to thank Mr. Sam Pino for his work in performing the blood spot filter paper iodine measurements.