Doctors Are Worried That Iodine Deficiency Is Coming Back

NEW YORK — 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.