Stefan Groeneweg was born on February 28th, 1989 in Rotterdam. He started his study of Medicine at the Erasmus University Medical Centre in Rotterdam. In September 2012 he obtained his Master degree in Molecular Medicine and in January 2016 he obtained his medical degree. During his studies, he entered the field of thyroid research at the laboratory of the thyroid expert prof. dr. ir. Theo Visser, where he performed his internship of his Master`s in Molecular Medicine. Following this exciting and inspiring collaboration, he started as a PhD candidate in 2014 and meanwhile continued his medical training. During these years, he was involved in many lines of research on thyroid hormone signalling, in particular thyroid hormone transport and metabolism. He has vast experience in basic research in the field of thyroidology, evidenced by numerous publications in this research field. He was the coordinating investigator on an investigator-initiated phase II clinical trial with the T3 analogue Triac in patients with defects in the thyroid hormone transport MCT8. Also, he was among the first to identify SLC17A4 as a novel thyroid hormone transporter and AADAT as a novel thyroid hormone metabolizing enzyme. After obtaining his docterate degree in 2020, he worked as a post-docteratal researcher in the Thyroid group of the Erasmus Medical Center, Rottedam, The Netherlands and started his clinical specialization in Paediatrics.