Hypothyroidism in neonates post-iodinated contrast media: a systematic review

Aim: To determine if neonates exposed to iodinated contrast media are at risk of hypothyroidism. Methods: A systematic review was conducted by searching electronic databases (e.g. MEDLINE), contacting experts and scanning reference lists. Studies examining the effects of contrast media on neonatal thyroid function were included. Two reviewers independently screened the literature and assessed the risk of bias, while one reviewer abstracted data. Results: Eleven studies were included; nine studies directly examined the risk of hypothyroidism (n = 182 neonates exposed to contrast media). All were highly affected by bias. In the three studies including term infants, one showed a trend towards increased thyroid-stimulating hormone (TSH) and decreased free thyroxine (FT4) among exposed groups. Six of 72 (8.3%) term infants exposed were treated for hypothyroidism. In studies of premature infants, there was a trend towards increased TSH (n = 3/7 studies), lower total thyroxine (n = 1), decreased triidothyronine and FT4 (n = 3) and hypothyroidism (n = 5). Twenty of 110 (18.2%) premature infants exposed were treated for hypothyroidism. Conclusion: Hospitalized neonates exposed to iodinated contrast media are at risk for abnormal thyroid function and development of hypothyroidism. Premature infants might be at increased risk. Well-controlled studies are required to replicate our findings because the included studies were highly affected by bias.