Hypothyroidism in Newborns From Overexposure to Iodine in the NICU

Simple measures can significantly reduce absorption of iodine and other chemicals

A recent article published in the Journal of Nutrition found that excessive exposure to iodine in the NICU is likely responsible for hypothyroidism in preterm infants.

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Hany Aly, MD, Chair of Neonatology at Cleveland Clinic Children’s agrees with this finding, citing previous studies showing that babies exposed to Betadine in the NICU tended to be hypothyroid.

“The issue of hypothyroidism in the NICU is definitely a problem,” he says. “Premature infants have low blood concentrations of thyroid hormones in their first week of life. In the NICU, they are exposed to iodine from topical antiseptics that is absorbed transcutaneously, taken up by the thyroid and inhibits the gland from producing thyroid hormone.”

Imaging contrast agents, although rarely used in the NICU, can have the same impact on the thyroid gland.

Cleveland Clinic NICU staff make a conscious effort to minimize exposure of premature infants to iodine. Efforts to find a suitable substitute for Betadine have produced mixed results. Chlorhexidine is an option, but neurotoxicity precludes its use in babies weighing less than 1000 grams (g).

While the search continues, Betadine remains the antiseptic of choice in infants with a birth weight less than 1000 g. “We don’t leave it on the skin. After allowing it to dry, it is thoroughly removed with sterile saline wipes,” says Dr. Aly.

Keeping chemicals out

Iodine absorption serves to illustrate a larger problem: That of the permeability of premature skin. In premature infants, the stratum corneum, or outer layer of skin, is incompetent or missing. Until this barrier forms, the infant is particularly vulnerable to the absorption of chemicals.

“When you apply any product to their skin, you should expect it to absorb some of the chemicals,” says Dr. Aly.

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While iodine absorption can be quickly detected and corrected, the impact of other chemical agents may not be apparent for years.

Studies suggest that about 15% of infants in the NICU experience neurodevelopmental delays and learning disabilities that cannot be explained by a specific disease entity.  Possible mechanisms leading to developmental delay include environmental exposures, such as lack of sleep, excessive noise and overhandling. “Certain chemicals may be responsible, as well,” says Dr. Aly. “When such agents affect the brain, the immediate impact may not be evident. However, they will have a long-term effect on brain development.”

Keeping fluids in

In addition to forming a barrier to keep chemicals out, skin helps the body retain fluid. Without fully developed skin, premature infants can lose excessive amounts of fluid, especially during their first week of life.

Vulnerability is enhanced by normal NICU procedures, such as attaching leads to the skin and drawing blood. “The average newborn weighing less than 1000 grams gets punctured 200 times in a NICU stay. That’s an unbelievable amount of torture to the skin,” says Dr. Aly.

The smaller the baby, the greater the risk. “Because the amount of skin in newborns is inversely proportional to weight, a very small infant will have greater surface area per kilogram of body weight. These babies tend to lose more fluid even faster than larger babies,” Dr. Aly explains.

Although it seems logical to use creams or moisturizers to create an artificial barrier and prevent skin from drying out, it has the opposite effect. “Studies have shown these products to attract bacteria, which cause infections,” he says.

Protecting the “forgotten organ”

Cleveland Clinic has found the health and development of tiny preemies is encouraged by doing as little to them as possible.

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“We minimize procedures and handling and maintain adequate humidity levels in the incubators,” says Dr. Aly. “These practices allow the skin—the “forgotten organ—to grow with minimal interruptions.”

In Cleveland Clinic’s NICU, routine lab tests do not exist. “An individualized approach in caring for these babies is of utmost importance,” he says. “We expect clinicians to think twice about the value of the information they anticipate receiving from a lab test before they order it, especially in relation to the potential harm from skin puncturing and pain induction.”

In addition, NICU staff minimize the use of tape on the skin.  Tape and lead removal is done gently without chemical solvents to protect the skin.

Going beyond protection

During the NICU stay, the goal should be to go beyond protecting the skin to nourishing it, says Dr. Aly.

“The skin of premature infants can be nourished by allowing kangaroo care, which puts the parents’ skin in contact with their baby’s skin. We encourage doing this as early as possible in the NICU stay,” he says.

Skin massage is offered routinely to premature infants later in the NICU course, after the infant is stabilized.  “We provide massage therapy by specialized caregivers, and we teach the parents how to carry on this practice after their infant graduates to home.”