Iodine disinfectant use in NICU may up risk of hypothyroidism in infants

July 21, 2020 0 By FM

Exposure to iodine used for medical procedures in a neonatal intensive care unit (NICU) may increase an infant’s risk for congenital hypothyroidism (loss of thyroid function), suggests a study led by researchers at the National Institutes of Health. The study is published in The Journal of Nutrition.

The authors found that infants diagnosed with congenital hypothyroidism following an NICU stay had higher blood iodine levels on average than infants who had an NICU stay but had normal thyroid function. 
“Limiting iodine exposure among this group of infants whenever possible may help lower the risk of losing thyroid function,” said the study’s first author, James L. Mills, MD, of the Epidemiology Branch at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).

Congenital hypothyroidism is a partial or complete loss of thyroid function. The thyroid, located in the throat, makes iodine-containing hormones that regulate growth, brain development and the rate of chemical reactions in the body. Treatment consists of thyroid hormone therapy and must begin within four weeks after birth or permanent intellectual disability may result.

Iodine solutions are commonly used as disinfectants to prepare the skin for surgical or other procedures. Preterm infants absorb iodine more readily through their skin than older infants. Iodine also is given internally for imaging procedures used in infants.

In the study, the researchers analyzed the iodine content in blood spots collected from the infants. They compared blood iodine levels from 907 children diagnosed with congenital hypothyroidism to those of 909 similar children who did not have the condition.

When the researchers considered only those infants with an NICU stay, they found that the group with congenital hypothyroidism had significantly higher iodine levels than those without the condition who also had an NICU stay. Similarly, those with congenital hypothyroidism and an NICU stay tended to have higher blood iodine than children with the condition who did not have a NICU stay.

The researchers said that the higher iodine levels seen among infants with congenital hypothyroidism and an NICU stay may have resulted from exposure to iodine during a medical procedure. The findings caution NICU staff to use disinfectants that do not contain iodine whenever possible and to avoid exposing infants to iodine unless absolutely necessary.