Dr Krenning completed his MD in 1972 and achieved a PhD by thesis at the University of Rotterdam in 1983. He has at present positions as Head of Department of Nuclear Medicine at the Erasmus University Medical Center, Rotterdam (since 1985), Professor of Nuclear Medicine (since 1990), and was made a Fellow of the Royal College of Physicians, London, UK, in 1999.

Dr Krenning has participated in the educational responsibilities at the Erasmus University Medical Center Rotterdam, lecturing in Internal Medicine, Nuclear Medicine and Endocrinology throughout his career. Dr Krenning has been involved in research since 1975. His main interests include thyroidology and radioactive labelled peptides with their introduction into imaging and radionuclide therapy. Dr Krenning has been the (co)author of more than 400 peer-reviewed articles since 1975, more than 300 chapters and proceedings in the field of thyroidology and peptide receptor scintigraphy and therapy.