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Edit this profileAt a glance
- 2112 Harrisburg Pike, Suite 202, Lancaster, PA 17601
About Dr. 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. The services billed most often include injection, infliximab, excludes biosimilar, 10 mg, removal of polyps or growths of large bowel using an endoscope with mechanical snare, and biopsy of large bowel using a flexible endoscope. The provider's National Provider Identifier (NPI) is 1003898131.
Factual summary compiled by Guide.md from public records; not written by this provider.
Education & Training
Specialty
Credentials & Licensing
Medicare information
Exactly as CMS reports it (National Downloadable File, Opt-Out Affidavits, Order & Referring). Not an insurance directory; confirm coverage with the office.
Contact Information
- (717) 544-3500
- Email not available
Practice Locations
2112 HARRISBURG PIKE SUITE 202
Lancaster, PA 17601
Conditions Commonly Evaluated or Treated
Within Gastroenterology generally. Availability varies by clinician, training and location — this profile has not been claimed, so nothing here is a personal claim by the provider.
Conditions
Most searched conditions
- Acid reflux
- Celiac disease
- Crohn's disease
- Hemorrhoids
- IBS
- Swallowing difficulties
- Ulcerative colitis
Biliary and pancreas
Colon and anorectal
Esophagus and swallowing
Functional bowel and motility
Liver
- Ascites
- Autoimmune hepatitis
- Cirrhosis
- Fatty liver disease
- Hemochromatosis
- Hepatitis B
- Hepatitis C
- Portal hypertension
Stomach and duodenum
Bowel & Colon
Digestive Symptoms
Gallbladder & Bile Ducts
Procedures & services
Most searched procedures
Lower endoscopy
Upper endoscopy
Capsule and physiology testing
Diagnostic Testing
Liver procedures
Treatments
Procedures Most Often Billed to Medicare
1,627 services · 472 patients · 13 distinct codes
| Procedure | Type | Code | Services | Compared with peers |
|---|---|---|---|---|
| Removal of polyps or growths of large bowel using an endoscope with mechanical snare | Procedure | 45385 |
102 | More often than most peers in Gastroenterology |
| Biopsy of large bowel using a flexible endoscope | Procedure | 45380 |
99 | More often than most peers in Gastroenterology |
| Biopsy of esophagus, stomach, and/or upper small bowel using a flexible endoscope | Procedure | 43239 |
71 | As often as other peers in Gastroenterology |
| Balloon dilation of esophagus, stomach, and/or upper small bowel using a flexible endoscope, less than 3.0 cm | Procedure | 43249 |
21 | As often as other peers in Gastroenterology |
| Dilation of esophagus | Procedure | 43450 |
19 | As often as other peers in Gastroenterology |
| Administration of chemotherapy into vein, each additional hour | Treatment | 96415 |
16 | Less often than most peers in Gastroenterology |
| Administration of chemotherapy into vein, 1 hour or less | Treatment | 96413 |
16 | Less often than most peers in Gastroenterology |
| Injection, infliximab, excludes biosimilar, 10 mg | Drug given | J1745 |
1,130 | Less often than most peers in Gastroenterology |
| Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more | Office visit | 99213 |
46 | As often as other peers in Gastroenterology |
| Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more | Office visit | 99214 |
42 | Less often than most peers in Gastroenterology |
Source: CMS Medicare public data. Shows how often procedures were billed — not quality of care or patient satisfaction.
Related providers
Connections drawn from the registry and from what providers have told us. A link here is not a referral or an endorsement.
Other gastroenterologists 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 gastroenterologists 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.
Common questions
What does Dr. Johnston specialize in?
Dr. Johnston is a gastroenterologist in Lancaster, PA. That is the designation recorded for this NPI in the federal registry, where it is listed 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. Contact the office directly to confirm availability and scheduling.
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.
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