Quick answers
- Does Tierney O. Brennan accept Medicare assignment?
- Medicare's clinician data says Tierney O. Brennan may accept Medicare assignment (as of October 2, 2026). Ask the office whether they accept it for your visit.
- What is Tierney O. Brennan's NPI number?
- 1831553023. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Practice locations
Addresses where Tierney O. Brennan is enrolled with Medicare (CMS data updated October 2, 2026).
- 225 E Chicago AveChicago, IL 60611
Specialties
- Nurse Practitionerprimary
Other nurse practitioners in Chicago
Clinicians with the same Medicare primary specialty in Chicago, IL — not a recommendation.
Clinician information
| Credential | NP |
|---|---|
| Graduation year | 2015 |
| Gender (as listed) | Female |
| Medicare assignment | May accept for some services |
| NPI (National Provider Identifier) | 1831553023 |
| 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
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- 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