Dr. Shiel received a bachelor of science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology. He is a fellow of the American Colleges of Physicians and Rheumatology.
Dr. Shiel retired in 2019 from clinical practice in the field of rheumatology in south Orange County, California with the Mission Heritage Medical Group. He has served as a teaching Associate Clinical Professor of Medicine at University of California, Irvine. He has also been chairman of the Department of Internal Medicine at Mission Hospital Regional Medical Center. He was selected as one of the most respected doctors in Orange County California in a poll of more than 5,000 physicians in the county performed by the Washington D.C. based Center for the Study of Services as published in Orange Coast magazine.
Dr. Shiel has authored and served as a reviewer for numerous articles on subjects related to arthritis for prestigious peer-reviewed medical journals and has published clinical rheumatology research. He has co-edited three medical textbooks. He is Co-Editor-In-Chief of three editions of the Webster's New World™ Medical Dictionary.
He has lectured in person and appeared on television and radio programs both for physicians and the local community. He was a medical commentator for the national news broadcast of medical issues related to the death of Pope John Paul II, Fox News NYC, April, 2005. He has authored numerous expert medical-legal reviews. He is a contributor for questions for the American Board of Internal Medicine. He is a regular reviewer of board questions on behalf of the American Board of Rheumatology Subspecialty. He served on the Medical and Scientific Committee of the Arthritis Foundation and the Medical Advisory Board of Lupus International.
Dr. Shiel was Chief Editor for the first 25 years of MedicineNet.com until July 2020 and a co-founder of the medical information website, MedicineNet.com. He has authored or edited over 15,000 articles for the website, now a subsidiary of WebMD.