Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
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Mark C. Nitzberg, MD

Individual provider Gastroenterology Physician · NPI 1881652758

Mark C. Nitzberg, MD practises Gastroenterology in Methuen, Massachusetts. Graduated from University of Massachusetts Medical School in 1989, 37 years ago. Practices as a sole proprietor, accepts Medicare assignment and offers telehealth. Licensed in Massachusetts.

Years since qualifying
37
Trained at
University of Massachusetts Medical School
Licensed in
MA
In the registry since
2006
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

38R Merrimack St Ste 2C
Methuen, MA 01844
Phone: (978) 681-1977
Fax: (978) 686-8918
Show map & directions

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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Gastroenterology Physician (primary) Taxonomy 207RG0100X · Licence 74584 (MA)

Record details

NPI number1881652758
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorYes
NPI enumeratedMay 2, 2006
Last updated in NPPESNovember 16, 2017

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyGASTROENTEROLOGY
Also practisesINTERNAL MEDICINE
Medical schoolUNIVERSITY OF MASSACHUSETTS MEDICAL SCHOOL
Graduated 1989 (37 years in practice)
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services
Practice locations4 on file with Medicare

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Colonoscopy 123 times · 84th percentile
Upper gastrointestinal (GI) endoscopy for acid reflux 44 times · 61st percentile

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients230
Services billed 311 a service is one billed item, such as a visit, a test or a procedure
Average patient age73

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician. Those with a page here are linked.

Other providers in Methuen