Quick answers
- Which hospitals does Rena D. Callahan work at?
- Medicare's official clinician data lists Rena D. Callahan at 4 hospitals: Henry Mayo Newhall Hospital, Ronald Reagan UCLA Medical Center, Santa Monica - UCLA Medical Center & Orthopaedic Hospital and UCLA West Valley Medical Center. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Rena D. Callahan see patients?
- Medicare's clinician data lists 6 practice locations, including Santa Monica, CA and Los Angeles, CA. Call before your visit to confirm the address.
- What is Rena D. Callahan's specialty?
- Medicare lists Hematology/Oncology as the primary specialty, and also Internal Medicine and Surgical Oncology.
- Does Rena D. Callahan accept Medicare assignment?
- Yes. Medicare's clinician data says Rena D. Callahan accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- Does Rena D. Callahan offer telehealth?
- Medicare's clinician data says Rena D. Callahan offers telehealth services. Ask the office which visits can be done by video or phone.
- What is the phone number for Rena D. Callahan?
- (424) 259-8859, as listed in official Medicare / NPI Registry data.
- What is Rena D. Callahan's NPI number?
- 1487856779. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Rena D. Callahan works
Medicare's Facility Affiliation Data lists Rena D. Callahan at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Henry Mayo Newhall HospitalValencia, CA · Acute Care Hospital · CCN 050624
- Ronald Reagan UCLA Medical CenterLos Angeles, CA · Acute Care Hospital · CCN 050262
- Santa Monica - UCLA Medical Center & Orthopaedic HospitalSanta Monica, CA · Acute Care Hospital · CCN 050112
- UCLA West Valley Medical CenterWest Hills, CA · Acute Care Hospital · CCN 050481
Practice locations
Addresses where Rena D. Callahan is enrolled with Medicare (CMS data updated 2026-10-02). The first 5 of 6; the Medicare profile lists all.
- 1223 16th StSanta Monica, CA 90404 (424) 259‑8859
- 1223 16th St, Suite 2101Santa Monica, CA 90404 (424) 259‑8859
- 2020 Santa Monica Blvd, Suite 210Santa Monica, CA 90404 (310) 458‑2381
- 2336 Santa Monica BlvdSanta Monica, CA 90404
- 757 Westwood PlzLos Angeles, CA 90095 (310) 267‑9643
Group practices
Medicare enrollment lists Rena D. Callahan as a member of this group (CMS data updated 2026-10-02).
- The Regents of the University of California1,462 clinicians in the group
Specialties
- Hematology/Oncologyprimary
- Internal Medicinealso
- Surgical Oncologyalso
Other hematologist-oncologists in Santa Monica
Clinicians with the same Medicare primary specialty in Santa Monica, CA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Perelman School Of Med At The University Of Pennsylvania |
| Graduation year | 2004 |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1487856779 |
| 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