Monitor children’s thyroids after iodine exposure for imaging, FDA says


The Food and Drug Administration has recommended thyroid monitoring for newborns and children through 3 years of age within 3 weeks of receiving injections of iodine-containing contrast media as part of imaging procedures.

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A recent FDA review showed that “underactive thyroid or a temporary decrease in thyroid hormone levels were uncommon,” according to an updated Drug Safety Communication issued on March 30, 2022.

However, early monitoring will help identify and treat any thyroid abnormalities as a result of the injections to help prevent potential complications in the future, according to the FDA, as babies and children do not generally show visible signs of thyroid problems and may not do so after an iodinated contrast media (ICM) injection.

ICM have been approved and used for decades to enhance images on x-rays or computed tomography (CT) scans, according to the communication.

The new FDA warning and recommendation for monitoring applies to the prescribing information for the entire class of ICM products. The new communication is an update to the 2015 Drug Safety Communication that advised medical professionals of the potential for underactive thyroid in response to ICM injections in newborns and young children. The update reflects new studies since that time.

The recent research showed that most reported cases of adverse effects were transient subclinical hypothyroidism and did not require treatment, according to the FDA. “The reported rate ranged from 1 percent to 15 percent and tended to be higher in neonates, particularly preterm neonates,” they said. Others at increased risk are those with underlying medical conditions, especially those with cardiac conditions who often require higher doses of contrast during invasive procedures.

In the recent studies, the time from ICM exposure to a diagnosis of thyroid dysfunction ranged from 8.5 to 138 days, but most occurred within 3 weeks, according to the update.

Patients and clinicians can report any adverse events from ICM or other medications to the FDA via FDA MedWatch program.

For more information, read the complete Drug Safety Communication.

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