Margaret L. McNairy, MD, MSc
David C. and Betty Farrell Professor of Medicine, Chief – Division of General Medicine & Geriatrics, and Chief – Division of Hospital Medicine
- Phone: 314-362-1700
- Fax: 314-362-9878
- Email: mcnairy@nospam.wustl.edu
Michael Lin, MD, SFHM
Section Chief of Hospital Medicine, Associate Professor of Medicine
- Phone: 314-362-1700
- Fax: 314-362-9878
Tong Yu, MD
Instructor in Medicine
- Phone: 314-362-1700
- Fax: 314-362-9878
Dr. Yu joined the Division of Hospital Medicine at Washington as an Instructor in Medicine in July 2024. She grew up in Iowa City, Iowa, and completed both undergraduate studies, medical education, and residency training in the Midwest. She attended college at Washington University in St. Louis and graduated cum laude in 2017 with a Bachelor of Science in Engineering in Biomedical Engineering. After college, she attended medical school at the University of Iowa Carver College of Medicine and received her medical degree in 2021. She was inducted into the Carver Humanism Honor Society in 2020. She then completed her residency training in Internal Medicine at the University of Iowa Hospitals and Clinics from 2021 to 2024. Her wide range of exposure and her various experiences during residency training pushed her interest toward hospital medicine, and she decided to pursue a career as an academic hospitalist.
Brenna Zack, NP
Nurse Practitioner
- Phone: 314-362-1700
- Fax: 314-362-9878
Brenna Zack, NP, is an Adult-Gerontology Acute Care nurse practitioner within the Division of Hospital Medicine. She received her BSN from Southeast Missouri State University in 2015. Her nursing experience includes time in acute care medicine and emergency medicine. She went on to receive her MSN from Maryville University in 2019 and joined the Division of Hospital Medicine in March 2020. She is committed to providing excellent patient care and furthering education for both nurse practitioner students and APCs within the division.
Samuel Zetumer, MD
Instructor in Medicine
- Phone: 314-362-1700
- Fax: 314-362-9878
Dr. Samuel Zetumer joined the Division of Hospital Medicine in the Department of Internal Medicine as a current Assistant Professor of Medicine in October 2025. He was born and raised in San Diego, California, and graduated cum laude from Princeton University with a degree in Mathematics. He then attended the University of California, San Francisco, where he obtained a medical degree and a master’s in clinical research and study design. Afterwards, he attended the University of Iowa for his internal medicine residency. Dr. Zetumer specializes in the creation and deployment of software to facilitate clinical research, enhance and monitor care quality, improve operational efficiency, and augment patient care directly. As the CHIO, Dr. Zetumer worked across multidisciplinary teams to upgrade clinical data servers safely, overhaul inpatient electronic medical record (EMR) functionality, translate primary research into dashboards for specialists to use during consultation, and migrated on-premise platforms to the VA’s Azure environment.
David Zhang, MD
Instructor in Medicine
- Phone: 314-362-1700
- Fax: 314-362-9878
David Zhang, MD joined the Division of Hospital Medicine in the Department of Internal Medicine as an Instructor in June 2025. He was raised in San Antonio, Texas. He attended Washington University in St. Louis, where he studied physics and graduated with college honors. During his time in college, was inducted into the physics honor society, Sigma Pi Sigma, and did research in biophysics and epigenetics. Zhang then completed his internship and residency at Barnes-Jewish Hospital / WashU School of Medicine prior to joining the division in 2025. During his time in residence, he has maintained an interest in medical education. His current interests are general internal medicine with a special interest in pulmonology and critical care. He is also eager to mentor trainees and students, and to further his interest in medical education.
Jiahua Zhang, DO
Instructor in Medicine
- Phone: 314-362-1700
- Fax: 314-362-9878
Dr. Jiahua Zhang joined the Division of Hospital Medicine as an Instructor in Medicine in July 2024. He was born and raised in Changsha, China, and came to the United States in 2011 for college. He attended the University of Washington in Seattle and graduated with a bachelor’s degree in biochemistry in 2015. After graduation, he worked as a lab technician, serving patients in need of diagnostic tests for 2 years. He started his medical training at Touro College of Osteopathic Medicine in Middletown, New York, in 2017 and received his medical degree in 2021. Dr. Zhang completed his residency in internal medicine at the Mercy Hospital in St. Louis in 2024 and joined the division in the same year. He was enthusiastic about developing clinical skills in using point-of-care ultrasound (POCUS) during his practice and received the certificate to perform a full-body POCUS exam during the third year of his residency. His clinical interests include general internal medicine with a focus on inpatient care, hematology and oncology, and the clinical education of medical students and residents.
Diana Zhao, MD, PhD
Assistant Professor of Medicine
- Phone: 314-362-1700
- Fax: 314-362-9878
Diana Zhao, MD, PhD is an Assistant Professor of Medicine in the Division of Hospital Medicine and works primarily as a night hospitalist. She has an interest in teaching and mentorship of students on the hospitalist service and aids in recruitment of internal medicine resident candidates through the IM program as an interviewer. She also serves on the Patient Care Operations Committee.
