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

Individual provider Geriatric Medicine (Internal Medicine) Physician · NPI 1811985633

Dr. Mark Stephan Ostrem, MD practises Internal Medicine in Quincy, Massachusetts. Graduated from University of Minnesota Medical School in 1976, 50 years ago. Practices with Pembroke Medical Associates Inc, a 26-clinician group and accepts Medicare assignment. Licensed in Massachusetts.

Years since qualifying
50
Trained at
University of Minnesota Medical School
Licensed in
MA
In the registry since
2005
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

54 Miller St Ste 300
Quincy, MA 02169-4725
Phone: (617) 481-3300
Fax: (617) 481-3305
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Geriatric Medicine (Internal Medicine) Physician (primary) Taxonomy 207RG0300X · Licence 44501 (MA)

Record details

NPI number1811985633
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedOctober 6, 2005
Last updated in NPPESJanuary 15, 2018

Medicare enrollment

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

Medicare specialtyINTERNAL MEDICINE
Also practisesGERIATRIC MEDICINE
Medical schoolUNIVERSITY OF MINNESOTA MEDICAL SCHOOL
Graduated 1976 (50 years in practice)
Group practice Pembroke Medical Associates Inc — 26 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount

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 patients215
Services billed 2,066 a service is one billed item, such as a visit, a test or a procedure
Average patient age74

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.

Payments from drug and device companies, 2025

Drug and device makers are required by federal law (the Physician Payments Sunshine Act) to report what they pay or give to clinicians, and CMS publishes the reports as Open Payments. This is the 2025 program year. A report is a record of a payment, not an allegation of anything, and many are small items such as meals. Only general payments are listed here; research payments and ownership or investment interests are reported separately by CMS and are not shown.

Food and Beverage $199 2 payments · a meal or drink at a meeting or visit, not a fee

Each amount is the sum of what companies reported for that kind of payment in 2025, rounded to the dollar. Not all of it is income to the clinician: a meal is not a fee, a charitable contribution goes to a charity, and a royalty or an acquisition payment is not a salary.

Check a report, or dispute one, at the source in CMS’s own tool, Open Payments. Corrections go through CMS’s dispute process. This site removes a home address on request and asks for no proof, because that is privacy; it will not remove an accurate payment report on request, because that is a statutory public disclosure.

Practises at

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

Colleagues at Pembroke Medical Associates Inc

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 26 clinicians in the practice; 12 are shown here.

Other providers in Quincy