Meet Our Care Team of Board-Certified Rheumatologists and Physician Assistants
Gilbert F. Gelfand, M.D.
Gilbert F. Gelfand, M.D. is a board-certified rheumatologist and fellow of the American College of Physicians (FACP) and the American College of Rheumatology (FACR). He is a Clinical Professor of Medicine at the Keck School of Medicine of University of Southern California (USC). He is also a Certified Clinical Densitometrist (CCD®) and is highly experienced in diagnosis and management of osteoporosis. He has been caring for patients in Whittier area and throughout the Southeast Los Angeles area for more than 30 years.
Dr. Gelfand studied medicine at the Autonomous University of Barcelona in Spain. He completed his medical training in the U.S. at Maimonides Medical Center and Coney Island Hospital, both in Brooklyn, New York. His Rheumatology training was completed at the Long Island College Hospital with rotations through the Hospital for Special Surgery (Cornell) and Downstate Medical Center.
Dr. Gelfand is presently serving as a Chief of Rheumatology at Rancho Los Amigos Medical Center. This is a USC teaching hospital where he actively participates in the training and education of rheumatology fellows and orthopedic residents for 30+ years.
He speaks both English and Spanish, and enjoys the opportunity to use both languages with his patients. In his free time, he is also an avid hiker/mountaineer, runner, reader and enjoys spending time with his wife and two daughters.
Branden Ireifej, M.D.
Branden Ireifej, M.D. is a board-certified rheumatologist and board certified internal medicine physician dedicated to providing comprehensive, compassionate care for patients with autoimmune and musculoskeletal conditions, including rheumatoid arthritis, lupus, psoriatic arthritis, gout, and vasculitis. Originally born in Yonkers, NY and raised in Upland, CA, Dr. Ireifej earned his undergraduate degree in Biology from the University of California, Riverside.
He went on to receive his medical degree from the American University of Antigua College of Medicine before completing his internal medicine residency at the Icahn School of Medicine at Mount Sinai – Elmhurst Hospital in Queens, NY. He then returned to Southern California to complete his rheumatology fellowship at the University of Southern California/Los Angeles General Medical Center.
Dr. Ireifej has contributed to several peer-reviewed publications and has presented his work at the American College of Rheumatology, where he was honored with the ARP President’s Choice Award in 2024. His approach to care emphasizes evidence-based medicine, thorough patient education, and shared decision-making to ensure each patient’s treatment plan is tailored to their needs and lifestyle. Proud to be back home in Southern California, Dr. Ireifej is committed to serving his community and helping patients achieve the best possible quality of life. Outside of medicine, he enjoys playing and watching basketball, running, traveling, exploring new restaurants, and spending time with his wife and daughter.
Susan Mansourian, M.D.
Susan Mansourian, M.D., FACR, graduated with summa cum laude from Debrecen Medical School in Hungary. After immigrating to the United States, she completed her residency in Internal Medicine at Rochester Regional Health-Unity Campus in Rochester, NY. She went on to complete her rheumatology fellowship at the University of Kentucky, where she refined her skills in diagnosing and managing complex rheumatologic conditions.
As a member of the American College of Rheumatology, Dr. Mansourian stays up-to-date on the latest advancements in the field and is committed to providing her patients with the highest level of care.
With her empathetic approach, Dr. Mansourian strives to provide each of her patients with individualized care, tailored to their unique needs. She is dedicated to helping patients achieve their best possible health outcomes, and she infuses her passion for rheumatology into every aspect of her practice.
Outside of her professional life, Dr. Mansourian enjoys expressing her artistic side through painting with watercolor and acrylic. She also values traveling and spending quality time with friends and family. She is fluent in English and Farsi.
Tien-I Karleen Su, M.D.
Tien-I Karleen Su, M.D., FACR, is a board-certified rheumatologist and a member of American College of Rheumatology. She studied medicine at the University of California, Los Angeles (UCLA) and completed her rheumatology fellowship at the Keck School of Medicine of University of Southern California (USC). While at UCLA medical school, she was elected into the Alpha Omega Alpha Medical Honor Society and has remained a member since.
She holds many leadership positions including Founder of Rheumatology Private Practice Alliance (RPPA), Chair of American College of Rheumatology Community Practice Council, and Board member of California Rheumatology Alliance. In all these roles, her mission is to empower current as well as new generations of rheumatologists to thrive in private practice and provide superior care to rheumatology patients.
Dr. Su is also a co-founder of Amicus Arthritis & Osteoporosis Center and a principle investigator of several clinical studies on rheumatological conditions including rheumatoid arthritis, lupus, psoriatic arthritis, osteoporosis, scleroderma, Sjogren’s Syndrome, and osteoarthritis. She has been treating patients in the Whittier area and throughout Southeast Los Angeles for more than ten years. She is passionate about serving the Whittier and nearby communities and sees herself practicing in this area for many more years to come. Dr. Su enjoys traveling, visiting museums, and photography (some of her photographs from her travels are featured here on our website). She speaks English, Spanish, and Mandarin.
Ericsson Trieu, PA-C
Ericsson Trieu, PA-C is a board-certified physician assistant. He graduated from UCLA with a bachelor's degree in physiologic science. He then worked as an EMT on an ambulance in both Orange and LA counties for 2 ½ years. He started his physician assistant training in Nevada in 2013 and relocated back to southern California in 2017.
He initially practiced in primary care where he learned the importance of providing comprehensive care to patients and became well versed in patient education. He brought these qualities to his position at Amicus Arthritis since 2017 where patients have described him as compassionate and detail-oriented. His hobbies include traveling, photography, trying out new foods, basketball, and spending time with his family and wife. He speaks English, Cantonese, and Spanish. We are delighted that Mr. Trieu has joined Amicus Arthritis to provide quality care to all of our rheumatology patients!
Julie Huang, PA-C
Julie Huang, PA-C is a board-certified physician assistant. She was born and raised in the San Francisco Bay Area and moved to Orange County to attend UC Irvine, where she graduated in 2019 with a bachelor’s degree in biological sciences. She later completed her physician assistant training at Western University in Pomona, CA in 2023. She has been apart of our team at Amicus Arthritis since 2024.
Julie is committed to patient education and empowering our patients to take charge of their own health. She speaks English and Cantonese and is learning Mandarin.
Julie enjoys traveling to see nature and visiting national parks. She spends much of her time outdoors, including hiking and off-roading. She goes skiing and snowboarding in the winter, and every spring, she starts a new vegetable garden. She is always excited to try new recipes and cuisines.
Stories From Our Clients