In 1973, he completed his Ph.D. thesis entitled Etude d'une endémie goitreuse en Afrique Centrale: Influence de la croissance et des facteurs d'environnement sur la fonction thyroïdienne.
He spent most of his professional career at the University Hospital Saint Pierre, eventually becoming Chief of Clinic and Professor of Pediatrics at the ULB, until he retired at the age of 60 years, in 1995.
He studied the iodine deficiency on a population level and showed role of cassava (manioc) and thiocyanate in endemic goiter and worked on the use of iodized oil in iodine deficiency disorders prevention.
[1] Furthermore, Delange was promoting ThyroMobil, an initiative to perform standardized thyroid volume measurement and urine iodine concentrations all over the world.
[1] During his career, Delange authored or co-authored 12 books and 361 publications, also he presented more than 200 communications at international meetings.