Our Team

Board Certified Family Medicine

Dr. Trevor Tsay, MD

I grew up here in Orange County and attended Villa Park High School. Following my roots, I pursued higher education, earning my Bachelor of Science in Biopsychology at the University of California, Santa Barbara. My journey in healthcare began at California Northstate University, College of Medicine, where I completed my medical education.

Driven by a desire to make a meaningful impact in patient care, I embarked on my residency training journey. Initially, I delved into General Surgery at U.C. Davis Medical Center in Sacramento, gaining valuable experience in the surgical realm. However, my true calling emerged as I transitioned to specialize in Family Medicine through UC Davis's satellite program in Modesto, CA.

Frustrated with the challenges posed by the corporate and insurance-driven healthcare system, I founded Amity Health with the vision of revitalizing family medicine. Committed to restoring the doctor-patient relationship, my team and I prioritize the compassionate foundation on which medicine was built. 

Outside of my professional pursuits, I find joy in motorsports, particularly Formula 1, and hockey. Cherished moments include spending time with my wonderful border collie, Remy.

Marshall MacDonald, MBA

I grew up in the Inland Empire receiving a bachelor's in environmental science from UC Santa Barbara and later receiving a Master’s in Business Administration from UC Riverside. I have been very active in my life doing everything from surfing, snowboarding, weightlifting, Brazilian Jiu Jitsu, and more. My health is something I have always valued highly as it has allowed me to delve myself into so many passions. Having had many injuries and being a patient through many insurance based systems, the 10 minute appointments and advice to stop doing the things I love were the reasons I found Direct Primary Care so fascinating. It allows patients to have a relationship with their doctor who thoroughly cares about the well-being of their patients. When Trevor approached me to help manage the practice, I was thrilled at the opportunity to be able to give patients a level of care that I was unaware was even possible in the current medical landscape.