Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.
NPIDirectory

Donald S. Diefendorf, PA-C

Individual provider Medical Physician Assistant · NPI 1437187002

Donald S. Diefendorf, PA-C is a Physician Assistant in Baltimore, Maryland. Qualified in 1998, 28 years ago. Practices with Wellspan Medical Group, a 2,342-clinician group, works from 2 locations, accepts Medicare assignment and offers telehealth. Licensed in Maryland and Pennsylvania.

Years since qualifying
28
Licensed in
MD, PA
In the registry since
2006
Specialties on file
2
What do these letters mean?
PA-C — Physician Assistant, Certified
A physician assistant who holds current national certification.

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Practice location Address checks out

2700 Quarry Lake Dr Ste 300
Baltimore, MD 21209
Phone: (410) 377-8900
Fax: (410) 377-0576
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Additional practice locations (1)

  • 1227 Baltimore St, Hanover, PA 17331-4406 — (717) 812-2055

Specialties & licences

Medical Physician Assistant (primary) Taxonomy 363AM0700X · Licence MA002841L (PA)
Medical Physician Assistant Taxonomy 363AM0700X · Licence C0002134 (MD)

Record details

NPI number1437187002
Entity typeIndividual (Type 1)
GenderMale
Credentials PA-C
Sole proprietorNo
NPI enumeratedJune 30, 2006
Last updated in NPPESDecember 5, 2025
Certification dateDecember 5, 2025

Medicare enrollment

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

Medicare specialtyPHYSICIAN ASSISTANT
Medical schoolOTHER
Graduated 1998 (28 years in practice)
Group practice Wellspan Medical Group — 2342 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services
Practice locations4 on file with Medicare

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 patients140
Services billed 493 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 $859 39 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.

Colleagues at Wellspan Medical Group

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 2342 clinicians in the practice; 12 are shown here.

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