The 13-year-old boy came to the clinic with a rapidly ballooning neck. Doctors were puzzled. 

Testing ruled out their first suspicion. But further tests pinpointed what they — and the boy — had been missing: iodine.

A century ago, iodine deficiency affected kids across large swaths of the country. It essentially disappeared after some food makers started adding it to table salt, bread and some other foods, in one of the great public health success stories of the 20th century.

But today, people are getting less iodine because of changes in diet and food manufacturing. 

Although most people are still getting enough, researchers have increasingly been reporting low levels of iodine in pregnant women and other people, raising concerns about an impact on their newborns. And there is also a very small, but growing, number of reports of iodine deficiency in kids.

“This needs to be on people’s radar,” said Dr. Monica Serrano-Gonzalez, a Brown University doctor who treated the boy in 2021 in Providence, Rhode Island.

Iodine is a trace element found in seawater and in some soils — mostly in coastal areas. A French chemist accidentally discovered it in 1811 when an experiment with seaweed ash created a purple puff of vapor. The name iodine comes from a Greek word meaning violet-colored.

Later that century, scientists began to understand that people need certain amounts of iodine to regulate their metabolism and stay healthy, and that it’s crucial in the development of brain function in children. 

One sign of insufficient iodine is a swelling of the neck, known as a goiter. The thyroid gland in the neck uses iodine to produce hormones that regulate the heart rate and other body functions. When there’s not enough iodine, the thyroid gland enlarges as it goes into overdrive to make up for the lack of iodine.

At the beginning of the 20th century, goiter was very common in children in certain inland parts of the United States, especially in a “goiter belt” that stretched from Appalachia and the Great Lakes to the northwest United States. Some of the kids were unusually short, deaf, intellectually stunted and had other symptoms of a syndrome once known as “cretinism.”