Mark H. Johnston, MD
Gastroenterology Physician · Lancaster, PA
Mark H. Johnston, MD is a gastroenterology physician with a practice address in Lancaster, Pennsylvania, and NPI 1003898131, issued on Nov 15, 2005. Check the license (Pennsylvania MD425522, as entered in NPPES) on the Pennsylvania Department of State (PALS); the Medicare figures below come from public CMS files.
- Name
- Mark H. Johnston
- Credential
- MD
- Primary taxonomy
- Gastroenterology Physician 207RG0100X
- License number
- MD425522 PA
Self-reported in NPPES; status is on the state search - Practice location
- 2112 Harrisburg Pike, Lancaster, PA 17601
- Phone
- (717) 544-3500
- Enumerated
- Nov 15, 2005
- Record last updated
- Jun 13, 2019 (not updated in 7 years: call before relying on the address or phone)
- Fax
- (717) 544-3501
- Medicaid IDs
- 1012082120002 PA
1012082120004 PA
1012082120005 PA - Medicare enrollment
- Enrolled (PECOS I20050831000030); accepts Medicare assignment
- Medical or professional school
- Hahnemann University College Of Medicine, 1985
- Entity
- Type 1 · individual
8 nearest gastroenterology physician records → All 1,049 in Pennsylvania → Look up another NPI →
Also registered at 2112 Harrisburg Pike
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Carly Albright Keller, CRNPFamily Nurse Practitioner1891166427
- Farida Aliyeva, CRNPNurse Practitioner1558014076
- Paul Allegretti, D.O.Gastroenterology Physician1033231907
- Anna Antwi, CRNPFamily Nurse Practitioner1083035190
- Ruthanne Ashworth, CRNPFamily Nurse Practitioner1134126881
- Terasa Astarita, CRNPAdult Health Nurse Practitioner1275530958
Verify Mark H. Johnston in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersPennsylvania Department of State (PALS)
Search for license MD425522Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
44% fewer Medicare Part D claims than the average gastroenterology physician in 2024
458 Medicare Part D claims for 155 beneficiaries, against an average of 811 among the 16,445 providers of this specialty who prescribed in Part D. Brand-name drugs were 5% of claims.
Most prescribed
- Omeprazole219 claims
- Pantoprazole Sodium68 claims
- Famotidine50 claims
- Esomeprazole Magnesium20 claims
- Mesalamine13 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Industry payments in 2024: $689.54
32 payments; by number, the most common kind was food and beverage; the largest payer was Abbvie Inc. The 13,350 providers of this specialty with any payment received $5,015.95 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
2 hospitals and group practices
- Lancaster General HospitalLancaster, PA · Acute Care Hospitals5 of 5 stars
- Regional Gastroenterology Associates OF Lancaster, Ltd.Lancaster, PA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through); hospitals matched to CMS Hospital General Information (Care Compare) (data.cms.gov). Star ratings are CMS hospital ratings, not ratings of this provider.
Mark H. Johnston among 1,049 gastroenterology physician records in Pennsylvania
Mark H. Johnston, MD is one of 1,049 gastroenterology physician records with a practice address in Pennsylvania. 85% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2005, is newer than 0% of them.
- NPI issued2005 · 0% of these records are older, 86% newer
- In a Medicare fileYes · 85% of these records are
- In the CMS Doctors and Clinicians fileYes · 73% of these records are
- Graduated1985 · median 2003 among the 769 with a school on file
- Record last updated2019 · 63% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RG0100X and a Pennsylvania practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Gastroenterology Physician providers in Pennsylvania
There are 1,049 gastroenterology physician records in Pennsylvania.
All 1,049 in Pennsylvania → Every provider in Lancaster → Gastroenterology Physician nationwide →
The 8 gastroenterology physician records with the nearest ZIP codes
- Richard Altman, MDLancaster, PA 176011689775413
- John Betteridge, M.D.Lancaster, PA 176011447354410
- Steve Chen, M.D.Lancaster, PA 176011053318600
- Richard Elkin, DOLancaster, PA 176011144318759
- John Horwhat, M.D.Lancaster, PA 176011487747242
- Rajeev Jayadevan, M.D.Lancaster, PA 176011598762387
- Ketan Kulkarni, MDLancaster, PA 176011710994231
- Ben Lazarus, DOLancaster, PA 176011922196518
Common questions
What is Mark H. Johnston, MD's NPI number?
Mark H. Johnston, MD's National Provider Identifier (NPI) is 1003898131, issued on Nov 15, 2005. An NPI identifies a provider in billing; it is not a license.
Where is Mark H. Johnston, MD located?
The NPPES record lists a practice address at 2112 Harrisburg Pike, Lancaster, PA, 17601. Phone: (717) 544-3500. Providers update this record themselves, so call before visiting.
How can I verify Mark H. Johnston, MD's license?
NPPES lists Pennsylvania license number MD425522, as entered by the provider. Search the Pennsylvania Department of State (PALS) at https://www.pals.pa.gov/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Mark H. Johnston, MD prescribe under Medicare Part D?
In 2024, Mark H. Johnston, MD had 458 Medicare Part D claims for 155 beneficiaries; the average among gastroenterology physician prescribers was 811. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.