Dr. Rengstorff was born and raised in the Bay Area. He attended medical school at Georgetown University School of Medicine and completed his residency at Vanderbilt University Medical Center. He later returned to the Bay Area to complete his fellowship in Gastroenterology at California Pacific Medical Center.

During his fellowship, Dr. Rengstorff was involved in studies evaluating the treatment of bleeding gastric varices and toxin-induced hepatitis. Dr. Rengstorff is married and has one son. While not involved in patient care, he enjoys golfing, skiing and woodworking