Physician Profile
Unclaimed ProfileAbout JOHNSTON
Mark H Johnston, MD practices gastroenterology in Lancaster, PA. Mark is a 1985 graduate of Hahnemann University College of Medicine. Medicare claims data shows Mark provided 1,627 services to 472 patients.
Summarised automatically from public NPI registry and CMS Medicare data. Not written or reviewed by this provider. Claim this profile to replace it.
Education & Training
Areas of Expertise
Common questions
What does Dr. Johnston specialize in?
Dr. Johnston is a gastroenterology in Lancaster, PA. This is the primary taxonomy recorded against the NPI in the federal registry, listed there as “GASTROENTEROLOGY”.
NPI registry
Where is Dr. Johnston located?
Dr. Johnston is listed at 2112 HARRISBURG PIKE SUITE 202, Lancaster, PA 17601. Addresses come from the NPI registry and can lag a move, so confirm before travelling.
NPI registry
What is Dr. Johnston's phone number?
The number on file is (717) 544-3500. Guide.md cannot book appointments or pass on messages — please call the office directly.
NPI registry
What is the NPI for Dr. Johnston?
Dr. Johnston's National Provider Identifier is 1003898131. It is issued by the Centers for Medicare & Medicaid Services and is unique and permanent — it does not change if they move practice.
NPI registry
Where did Dr. Johnston go to medical school?
Dr. Johnston attended Hahnemann University College of Medicine, graduating in 1985. This comes from the CMS National Downloadable File.
CMS public data
How much experience does Dr. Johnston have?
Dr. Johnston has 41 years experience. Calculated from a graduation year of 1985, reported in the CMS National Downloadable File.
CMS public data
What does Dr. Johnston do most often?
According to Medicare billing data, Dr. Johnston performs procedures including removal of polyps or growths of large bowel using an endoscope with mechanical snare, biopsy of large bowel using a flexible endoscope and biopsy of esophagus, stomach, and/or upper small bowel using a flexible endoscope; provides treatments such as administration of chemotherapy into vein, each additional hour and administration of chemotherapy into vein, 1 hour or less, alongside routine visits and testing. This reflects Medicare patients only and is billing volume, not a measure of quality.
Medicare claims
Is Dr. Johnston's profile verified?
Not yet. This profile is built from public federal data and has not been confirmed by Dr. Johnston. If this is you, claiming it is free.
Guide.md
Licensing & Certification
Source: NPPES NPI Registry
Contact Information
- (717) 544-3500
- Email not available
Practice Locations
2112 HARRISBURG PIKE SUITE 202
Lancaster, PA 17601
Procedures Most Often Billed to Medicare
1,627 services · 472 patients · 13 distinct codes
| Procedure | Type | Code | Services |
|---|---|---|---|
| Removal of polyps or growths of large bowel using an endoscope with mechanical snare | Procedure | 45385 |
102 |
| Biopsy of large bowel using a flexible endoscope | Procedure | 45380 |
99 |
| Biopsy of esophagus, stomach, and/or upper small bowel using a flexible endoscope | Procedure | 43239 |
71 |
| Balloon dilation of esophagus, stomach, and/or upper small bowel using a flexible endoscope, less than 3.0 cm | Procedure | 43249 |
21 |
| Dilation of esophagus | Procedure | 43450 |
19 |
| Administration of chemotherapy into vein, each additional hour | Treatment | 96415 |
16 |
| Administration of chemotherapy into vein, 1 hour or less | Treatment | 96413 |
16 |
| Injection, infliximab, excludes biosimilar, 10 mg | Drug given | J1745 |
1,130 |
| Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more | Office visit | 99213 |
46 |
| Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more | Office visit | 99214 |
42 |
Source: CMS Medicare public data. Shows how often procedures were billed — not quality of care or patient satisfaction.
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Claim this profileRelated providers
Connections drawn from the registry and from what providers have told us. A link here is not a referral or an endorsement.
Other gastroenterology specialists at this location 7
Same specialty, same street address — most likely the same department or group.
Related specialists at this location 1
Clinically related specialties at the same address — the people this provider most likely works alongside.
Also at this address 4
Providers at the same street address. Each files their own registry entry, so a shared practice often appears under several different names.
More connections — 29 related providers in 4 groups
Other gastroenterology specialists in Lancaster 5
Same specialty, same city.
Trained at Hahnemann University College of Medicine 8
Other providers in the same specialty who trained at the same institution.
Class of 1985 at Hahnemann University College of Medicine 8
Providers who graduated from the same medical school in the same year.
Also performs Removal of polyps or growths of large bowel using an endoscope with mechanical snare 8
Providers in PA who bill this service to Medicare most often.
Provider data sourced from the NPPES NPI Registry and CMS public datasets. Information is provided for reference and is not medical advice.