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

Individual provider Emergency Medicine Physician · NPI 1053330431

Mary Antionette Fitzsimons, MD practises Emergency Medicine in Antioch, California. Graduated from Northwestern University Feinberg Medical School in 1981, 45 years ago. Practices with Cep America - California, a 1,267-clinician group and accepts Medicare assignment. Licensed in California.

Years since qualifying
45
Trained at
Northwestern University Feinberg Medical School
Licensed in
CA
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

3901 Lone Tree Way
Antioch, CA 94509-6200 Not confirmed with CMS for 18 years — call before visiting
Phone: (925) 779-7273
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Emergency Medicine Physician (primary) Taxonomy 207P00000X · Licence G56339 (CA)

Record details

NPI number1053330431
Entity typeIndividual (Type 1)
GenderFemale
Credentials MD
Sole proprietorNo
NPI enumeratedJuly 18, 2006
Last updated in NPPESOctober 24, 2007

Medicare enrollment

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

Medicare specialtyEMERGENCY MEDICINE
Medical schoolNORTHWESTERN UNIVERSITY FEINBERG MEDICAL SCHOOL
Graduated 1981 (45 years in practice)
Group practice Cep America - California — 1267 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 patients470
Services billed 809 a service is one billed item, such as a visit, a test or a procedure
Average patient age72

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.

Colleagues at Cep America - California

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 1267 clinicians in the practice; 12 are shown here.

Other providers in Antioch