Popper spent his five postgraduate years in anatomical pathology and established a
biochemical laboratory, which was a new field of medical research. He worked under the famous Viennese physician Professor
Hans Eppinger, under whose influence he developed his interest in hepatology. One of his main achievements of this period was the
creatinine clearance test to assess
renal function. He became Scientific Director for the
Hektoen Institute for Medical Research and Professor of Pathology at
Northwestern University School of Medicine. He was the driving force behind the founding of the
American Association for the Study of Liver Diseases, which first met in 1948. In 1957, he was appointed pathologist-in-chief at the
Mount Sinai Hospital in New York, succeeding
Paul Klemperer. There, he was pivotal in founding the
Mount Sinai School of Medicine, becoming its first dean. In 1973, he became the Gustave L. Levy Distinguished Service Professor and maintained this position until his death. == Publications ==