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

Dr. Nathan Daniel Mark, DO

Individual provider Anesthesiology Physician · NPI 1902973993

Dr. Nathan Daniel Mark, DO practises Anesthesiology in Hartford, Connecticut. Graduated from New York College of Osteo Medicine of New York Institute of Technology in 2005, 21 years ago. Practices with Catholic Health Initiatives Colorado, a 1,266-clinician group, works from 2 locations and accepts Medicare assignment. Licensed in Colorado and Connecticut.

Years since qualifying
21
Trained at
New York College of Osteo Medicine of New York Institute of Technology
Licensed in
CO, CT
In the registry since
2006
Specialties on file
2
What do these letters mean?
DO — Doctor of Osteopathic Medicine
A fully licensed physician, trained like an MD with additional musculoskeletal training. Equivalent practice rights in all 50 states.

See every abbreviation used in this directory →

Claim this listing Report a problem Suggest an edit

Practice location Address checks out

80 Seymour St
Hartford, CT 06106-3315
Phone: (860) 545-2117
Show map & directions

Directions in Google Maps · Apple Maps · OpenStreetMap

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

Additional practice locations (1)

  • 1010 Three Springs Blvd, Durango, CO 81301-8296 — (970) 761-3200

Specialties & licences

Anesthesiology Physician (primary) Taxonomy 207L00000X · Licence 050791 (CT)
Anesthesiology Physician Taxonomy 207L00000X · Licence CDRH.0057872 (CO)

Record details

NPI number1902973993
Entity typeIndividual (Type 1)
GenderMale
Credentials DO
Sole proprietorNo
NPI enumeratedNovember 29, 2006
Last updated in NPPESOctober 3, 2024
Certification dateOctober 3, 2024

Medicare enrollment

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

Medicare specialtyANESTHESIOLOGY
Medical schoolNEW YORK COLLEGE OF OSTEO MEDICINE OF NEW YORK INSTITUTE OF TECHNOLOGY
Graduated 2005 (21 years in practice)
Group practice Catholic Health Initiatives Colorado — 1266 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 patients346
Services billed 393 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.

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 $49 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 Catholic Health Initiatives Colorado

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 1266 clinicians in the practice; 12 are shown here.

Other providers in Hartford