Mark H. Johnston, MD, FACP, FACG, AGAF

Mark H. Johnston, MD, FACP, FACG, AGAF

Areas of Interest

Gastroesophageal Reflux Disease (GERD), Barrett’s Esophagus, Esophageal Cancer, CryoSpray Ablation Therapy.


Hahnemann University


Portsmouth Naval Medical Center


Portsmouth Naval Medical Center


National Naval Medical Center, Bethesda, MD

Board Certification

Internal Medicine and Gastroenterology

Biographical Info

Dr. Johnston earned his MD at Hahnemann University. He completed his Residency at Naval Medical Center Portsmouth and his Fellowship in Gastroenterology at National Naval Medical Center, Bethesda, MD.

He is former Chief of Gastroenterology at the National Naval Medical Center, Bethesda, MD, and retired as a Navy Captain in 2005. He has treated numerous members of Congress, the Supreme Court and White House.

Dr. Johnston is board certified in Internal Medicine and Gastroenterology and is a Fellow of the American College of Physicians, American College of Gastroenterology and Fellow of the American Gastroenterological Association. He has been practicing gastroenterology in Lancaster County since 2005.

He is the author of numerous publications and is internationally known for his expertise in esophageal disease. He has several U.S. Patents for his invention of CryoSpray Ablation Therapy. This technique uses a spray of liquid nitrogen to treat cancerous and precancerous conditions of the esophagus including Barrett’s Esophagus and esophageal cancer. He has spoken nationally and internationally in his areas of research: GERD, Barrett’s Esophagus and esophageal cancer.

He has privileges at Penn Medicine Lancaster General Hospital, WellSpan Ephrata Community Hospital and UPMC Pinnacle Lititz.

He and his wife live in Lancaster. They have three children; two sons who are active-duty medical officers in the Navy and a daughter who is a Physician Assistant. In his free time, he enjoys spending time with his family, the outdoors, hiking and sailing. He has led and served in over 30 medical mission trips to Kenya, China and Albania.

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