Internist at the Charité hospital in Berlin. After the National Socialists came to power, Arnoldi lost his position as chief physician. He initially remained in Berlin and was imprisoned in the Sachsenhausen concentration camp from November 11, 1938 to December 16, 1938. In March 1939 he fled with his family to Copenhagen. In 1943 he came to Sweden, where he was again active in clinical science. He found employment at Länssjukhuset Ryhov, the largest hospital in Jönköping. After his retirement, he returned to Denmark.
