Rochester, Minnesota - Some medical discoveries stand the test of time. The case of a dedicated Mayo Clinic chemist is a prime example. Feeling that he was on the verge of a breakthrough that could help countless people, Dr. Edward Kendall spent Christmas Eve 1914 locked away in his lab. What he accomplished by Christmas morning was a gift to millions of thyroid patients, one that is still improving lives a century later. Dennis Douda has this inspiring story.

Watch: A Christmas Gift for Thyroid Patients