Mark JohnstonMD
Gastroenterology·Lancaster, PA
Mark Johnston, MD is a Gastroenterology provider in Lancaster, PA, as of July 2026.
- NPI1003898131
- Registered2005
- Class of1985
Case volumes, referral patterns, and payer mix live in DataLily AI Insights.
Education
Education on record as of August 2026.
Mark Johnston at a glance
- Provider
- Mark Johnston
- Credential
- MD
- Specialty
- Gastroenterology
- Procedures
- Gastroenterology CPT codes
- Location
- Lancaster, PA
- Medical school
- Hahnemann University College of Medicine
- Graduated
- 1985
- NPI registered
- 2005
- NPI
- 1003898131
- Snapshot
- July 2026
Identity, specialty, and affiliations change over time. This is not an endorsement, and not clinical, billing, or legal advice. Providers may request corrections at founders@datalilyai.com. Read the DataLily AI data methodology.
Questions
Where does Mark Johnston practice?
Mark Johnston, MD is based in Lancaster, PA. Affiliations reflect the current DataLily AI snapshot (July 2026) and can change.
What is Mark Johnston's NPI number?
Mark Johnston's National Provider Identifier (NPI) is 1003898131, registered in 2005. Specialty on record: Gastroenterology; credential MD.
Where did Mark Johnston go to medical school?
Mark Johnston, MD attended Hahnemann University College of Medicine, graduating in 1985.
How many Gastroenterology providers in Pennsylvania work at ambulatory surgery centers?
186 Gastroenterology surgeons and proceduralists in Pennsylvania are affiliated with ambulatory surgery centers in DataLily AI's current snapshot, Mark Johnston among them. The Pennsylvania Gastroenterology directory lists each one by city with credential, NPI, and center affiliations.
Pilot Analysis
Get the complete Mark Johnston analysis
Tell us where to send it. Our team will prepare an analysis of Mark Johnston covering case volumes, referral patterns, payer mix, and how specialty peers compare, and email it to you within 5-10 business days. Need it faster? Book a demo.