Quick answers
- Which hospitals does Thomas O'Callaghan work at?
- Medicare's official clinician data lists Thomas O'Callaghan at 2 hospitals: Chelsea Hospital and University of Michigan Health System. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Thomas O'Callaghan see patients?
- Medicare's clinician data lists 13 practice locations, including Ann Arbor, MI. Call before your visit to confirm the address.
- What is Thomas O'Callaghan's specialty?
- Medicare lists Internal Medicine as the primary specialty.
- Does Thomas O'Callaghan accept Medicare assignment?
- Yes. Medicare's clinician data says Thomas O'Callaghan 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.
- What is the phone number for Thomas O'Callaghan?
- (734) 936-5738, as listed in official Medicare / NPI Registry data.
- What is Thomas O'Callaghan's NPI number?
- 1265926331. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Thomas O'Callaghan works
Medicare's Facility Affiliation Data lists Thomas O'Callaghan at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Chelsea HospitalChelsea, MI · Acute Care Hospital · CCN 230259
- University of Michigan Health SystemAnn Arbor, MI · Acute Care Hospital · CCN 230046
Practice locations
Addresses where Thomas O'Callaghan is enrolled with Medicare (CMS data updated 2026-10-02). The first 5 of 13; the Medicare profile lists all.
- 1500 E Medical Ctr, Suite 0331Ann Arbor, MI 48109 (734) 936‑5738
- 1500 E Medical Ctr 2nd Floor Rec, Taubman CenterAnn Arbor, MI 48109 (734) 936‑5020
- 1500 E Medical Ctr DrAnn Arbor, MI 48109
- 1500 E Medical Ctr Dr 1st Fl, Taubman Ctr Rec DAnn Arbor, MI 48109 (734) 936‑4185
- 1500 E Medical Ctr Dr 1st Fl Rec D, Taubman CenterAnn Arbor, MI 48109 (734) 764‑5175
Group practices
Medicare enrollment lists Thomas O'Callaghan as a member of these groups (CMS data updated 2026-10-02).
- Regents of the University of Michigan3,346 clinicians in the group
- Chelsea Community Hospital41 clinicians in the group
Specialties
- Internal Medicineprimary
Other internal medicine doctors in Ann Arbor
Clinicians with the same Medicare primary specialty in Ann Arbor, MI — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Michigan Medical School |
| Graduation year | 2022 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1265926331 |
| 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