Low thyroid activity, one of the most treated conditions in the United States, may actually be a sign of longevity, researchers say.

While they said it was far too soon for people taking thyroid pills to stop, they will be looking to see if the thyroid may hold the key to a long life, at least for some people.

Dr Martin Surks and colleagues at the Montefiore Medical Center and the Albert Einstein College of Medicine in New York studied hundreds of people who had lived to be 100, and found evidence that people with low thyroid activity were more likely to be in that group.