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

Gretchen K Mathewson, FNP

Individual provider Family Nurse Practitioner · NPI 1639494685

Gretchen K Mathewson, FNP is a Nurse Practitioner in New York, New York. Qualified in 2009, 17 years ago. Practices with Icahn School of Medicine at Mount Sinai, a 2,791-clinician group, accepts Medicare assignment and offers telehealth. Licensed in New York.

Years since qualifying
17
Licensed in
NY
In the registry since
2010
What do these letters mean?
FNP — Family Nurse Practitioner
A nurse practitioner who treats patients of all ages, much like a family doctor.

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Practice location Address checks out

5 E 98th Street Box 1138
New York, NY 10029-6501 Not confirmed with CMS for 15 years — call before visiting
Phone: (212) 241-6854
Fax: (212) 241-5333
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Family Nurse Practitioner (primary) Taxonomy 363LF0000X · Licence F335831 (NY)

Record details

NPI number1639494685
Entity typeIndividual (Type 1)
GenderFemale
Credentials FNP
Sole proprietorYes
NPI enumeratedApril 1, 2010
Last updated in NPPESOctober 25, 2010

Medicare enrollment

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

Medicare specialtyNURSE PRACTITIONER
Medical schoolOTHER
Graduated 2009 (17 years in practice)
Group practice Icahn School Of Medicine At Mount Sinai — 2791 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services
Practice locations2 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 patients19
Services billed 38 a service is one billed item, such as a visit, a test or a procedure
Average patient age61

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 $89 1 payment · 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 Icahn School of Medicine at Mount Sinai

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 2791 clinicians in the practice; 12 are shown here.

Other providers in New York