Iodine Contrasting Agent Side Effects May Cause Thyroid Problems in Infants: FDA

Exposure to iodine-based contrasting agents, such as Conray, Ultravist, and Cystografin, may increase the risk of underactive thyroids among infants, federal drug regulators warn. 

In a drug safety communication issued on Tuesday, the FDA indicates that it has detected rare cases of underactive thyroid in infants after they were given contrast dye containing iodine.

The FDA has ordered the manufacturers of 10 iodine-containing contrast dyes to update their drug’s label warnings and is requiring the manufacturers of 10 contrast dyes to conduct additional studies.

Iodine contrast media (ICM) products are used to give better results when x-rays and other medical imaging scans are needed. It is designed to allow doctors and medical technicians to better see blood vessels and organs when those scans are taken.

The FDA conducted a search of its adverse events database and found that, while rare, there appeared to be an association between iodine-containing contrast dye exposure and underactive infant thyroid cases. The search turned up 10 cases between 1969 and early 2012 that were reported. However, medical experts say that reports to the FDA’s Adverse Event Reporting System (FAERS) only receives a small fraction of the actual adverse events that occur in medical practice.

An analysis of the reports found that all of the cases involved infants who were either premature or suffering from other serious underlying medical conditions, but those may not account for the underactive thyroids, the FDA warned. All were diagnosed with underactive thyroids less than a month after receiving an ICM, though some involved a topical ICM that is no longer recommended for infant use.

The side effects of an underactive thyroid, known as hypothyroidism, can include fatigue, constipation, dry skin, unexplained weight gain and a sensitivity to cold. The FDA determined that the effects are temporary and usually resolve without treatment.

“We have approved changes to the labels of all iodinated contrast media (ICM) products to include information about these cases. We do not recommend changes to current prescribing, administration, or monitoring practices,” the FDA safety warning states. “We will continue to evaluate this issue and will update the public when we have additional information.”

The ICMs affected by the label changes include:

• Cystografin and Cystografin Dilute (diatrizoate meglumine)
• MD-76R (diatrizoate meglumine and diatrizoate sodium)
• Cholografin Meglumine (iodipamide meglumine)
• Visipaque (iodixanol)
• Omnipaque (iohexol)
• Isovue, Isovue-M, Scanlux (iopamidol)
• Ultravist (iopromide)
• Conray (isothalamate meglumine)
• Optiray (ioversol)
• Hexabrix (ioxaglate meglumine and ioxaglate sodium)
• Oxilan (ioxilan)