Quick answers
- Which hospitals does John Patresan work at?
- Medicare's official clinician data lists John Patresan at 1 hospital: Contra Costa Regional Medical Center. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does John Patresan see patients?
- Medicare's clinician data lists 1 practice location in Martinez, CA. Call before your visit to confirm the address.
- What is John Patresan's specialty?
- Medicare lists Hematology/Oncology as the primary specialty.
- Does John Patresan accept Medicare assignment?
- Medicare's clinician data says John Patresan may accept Medicare assignment (as of 2026-10-02). Ask the office whether they accept it for your visit.
- What is John Patresan's NPI number?
- 1023644978. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where John Patresan works
Medicare's Facility Affiliation Data lists John Patresan at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Contra Costa Regional Medical CenterMartinez, CA · Acute Care Hospital · CCN 050276
Practice locations
Addresses where John Patresan is enrolled with Medicare (CMS data updated 2026-10-02).
- 331 C StMartinez, CA 94553
Specialties
- Hematology/Oncologyprimary
Other hematologist-oncologists in California
Clinicians with the same Medicare primary specialty in California — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 2020 |
| Gender (as listed) | Male |
| Medicare assignment | May accept for some services |
| NPI (National Provider Identifier) | 1023644978 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians