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Excess iodine increases hypothyroidism risk in infants with congenital heart disease
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Infants with congenital heart disease exposed to excess iodine have an increased risk for hypothyroidism accompanied by a risk for multiple procedures and impaired renal function, study data show.
Vidhu V. Thaker, MD, of the division of endocrinology at Boston Children’s Hospital, and colleagues evaluated data on 183 infants younger than 1 month with congenital heart disease and at least one thyroid-stimulating hormone value available for analysis between 2009 and 2012. Researchers sought to determine the proportion of participants with congenital heart disease who developed hypothyroidism after iodine exposure from cardiac catheterization and cardiac surgery and to identify risk factors for development of hypothyroidism.
Overall, 40% of participants underwent cardiac catheterization only during the iodine exposure period, 49% underwent both cardiac catheterization and cardiac surgery, and 11% underwent cardiac surgery only during the exposure period and cardiac catheterization after the exposure period.
From the time of the first iodine exposure, serial thyroid function tests were available for analysis for a median of 14 days, and 46 participants were diagnosed with hypothyroidism at a median of 8.5 days after exposure. Participants were a median postnatal age of 3 days on the day of their first procedure, and median gestational age was 38.7 weeks. Cyanotic heart defects were the most common (58%), followed by congenital anomalies or genetic syndromes (25%). By the end of follow-up, 21% of participants died, 30% with hypothyroidism and 18% without hypothyroidism (P = .06).
The risk for hypothyroidism was increased in participants with serum creatinine levels greater than 0.9 mg/dL compared with those with lower levels (OR = 4.22; 95% CI, 1.61-11.05) and in those who underwent more than three procedures compared with those who underwent fewer (OR = 3.65; 95% CI, 1.48-9.02), after controlling for baseline risk, postnatal age and gestational age.
“Systematic monitoring of thyroid function in all neonates at close intervals after exposure to excess iodine is warranted,” the researchers wrote. “Future studies investigating the optimal frequency and timing of screening and the association between severity and duration of hypothyroidism and neurocognitive function in these infants are needed.” – by Amber Cox
Disclosures: The researchers report no relevant financial disclosures.
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