Dr. O'Connor is a board certified Internal Medicine physician and a Clinical Instructor of Medicine at the University of Connecticut School of Medicine. He is a published academic researcher, the creator of a personalized healthcare app: Testosteronology.com, and the author of "America on Steroids: A Time to Heal."

Through his practice, ThomasOConnorMD.com, he offers internist medical consultation and medical services in the fields of hypertension, diabetes, hypercholesterolemia, cardiovascular disease evaluation, men's health, testosterone replacement, erectile dysfunction, sexual dysfunction.

He is also known as the “Anabolic Doc” due to his skill and experience in caring for men on TRT and anabolic steroids. His expertise in this area has been sought by the world's top media outlets, including The New York Times, Medscape,  National Geographic, Hulu, Generation Iron, Muscle and Fitness, Vice TV, and more.