Exposure to iodine in the neonatal intensive care unit (NICU) may increase a baby's risk for loss of thyroid function, a new study suggests.
Iodine solutions are often used as disinfectants on the skin before surgical or other medical procedures. Iodine also is given internally for imaging procedures used in infants, researchers explained.
Investigators found higher blood levels of iodine in babies with congenital hypothyroidism (partial or total loss of thyroid function) who had had a stay in the NICU. All these infants had normal thyroid function when they went to the NICU.
"Limiting iodine exposure among this group of infants whenever possible may help lower the risk of losing thyroid function," researcher Dr. James Mills said in a news release from the U.S. National Institutes of Health.
Mills is from the epidemiology branch of the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development.
For babies with congenital hypothyroidism, treatment with thyroid hormone has to start within four weeks after birth or permanent intellectual disability can happen.
For the study, Mills and his colleagues compared iodine levels from more than 900 children with congenital hypothyroidism to more than 900 children who did not have the condition.
Among the kids, 183 were cared for in the NICU. Of these, 114 had congenital hypothyroidism and 69 did not.
Children with congenital hypothyroidism were more likely to have been in a NICU than those without the condition, the researchers found.
When they looked at only kids who had been in the NICU, they found those with congenital hypothyroidism had higher iodine levels than those without the condition.
Higher iodine levels among babies with congenital hypothyroidism and a NICU stay might be linked to exposure to iodine during treatment, although only an association was observed and the research didn't include information on the infants' exact medical procedures.
The researchers caution NICU staff not to use disinfectants containing iodine and to avoid exposing babies to iodine unless necessary. Preemie infants absorb iodine more readily through their skin than older infants, they noted.
The report was published July 7 in the Journal of Nutrition.
For more on congenital hypothyroidism, head to the U.S. Department of Health and Human Services .