DR. MICHAEL JAMES BRENNAN DO, MPH
NPI 1811550981
Internal Medicine - Critical Care Medicine in Chicago, IL
About Dr. Michael James Brennan Do, Mph NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
DR. MICHAEL JAMES BRENNAN DO, MPH (NPI 1811550981) is an individual critical care medicine provider in Chicago, Illinois, licensed in Illinois (036.164300) and active in the NPI registry since April 2019. He is enrolled in Medicare PECOS, is affiliated with Advocate Trinity Hospital, and maintains 4 additional practice locations.
NPPES Registry Identity
Specialties & Licenses 2
Secondary Practice Locations 4
Accepted Insurance
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare and accepts Medicare assignment
Dr. Michael James Brennan Do, Mph is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.
Medicare Billing Reassignments
11Medicare enrollment records show Michael Brennan reassigns Medicare billing to 11 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Chicago, IL 60612
- Reassigned Medicare billing, Illinois enrollment
- 2,169 clinicians in this Medicare group
Chicago, IL 60612
- Reassigned Medicare billing, Illinois enrollment
- 548 clinicians in this Medicare group
Chicago, IL 60608
- Reassigned Medicare billing, Illinois enrollment
- 982 clinicians in this Medicare group
Chicago, IL 60623
- Reassigned Medicare billing, Illinois enrollment
- 24 clinicians in this Medicare group
Chicago, IL 60624
- Reassigned Medicare billing, Illinois enrollment
- Medicare enrollment name: Advocate Health And Hospitals Corporation
- 4,870 clinicians in this Medicare group
Oak Park, IL 60304
- Reassigned Medicare billing, Illinois enrollment
- 124 clinicians in this Medicare group
Kankakee, IL 60901
- Reassigned Medicare billing, Illinois enrollment
- 61 clinicians in this Medicare group
Sterling, IL 61081
- Reassigned Medicare billing, Illinois enrollment
- 356 clinicians in this Medicare group
Cedar Falls, IA 50613
- Reassigned Medicare billing, Iowa enrollment
- 20 clinicians in this Medicare group
Cedar Falls, IA 50613
- Reassigned Medicare billing, Iowa enrollment
- 37 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Areas of Expertise CMS Part B claims 2
Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.
Hospital Affiliations CMS Care Compare 3
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
Advocate Trinity Hospital
Acute Care Hospitals · Chicago, ILRush Oak Park Hospital
Acute Care Hospitals · Oak Park, ILAdvocate Christ Hospital & Medical Center
Acute Care Hospitals · Oak Lawn, ILPhysician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 60612 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
Other Providers at the Same Location NPPES 20
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
CHICAGO, IL 60612
Frequently Asked Questions NPPES & CMS
Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.
What is Michael Brennan's NPI number?
The NPI number for Michael Brennan is 1811550981. It was assigned to this individual provider in the NPPES registry on April 15, 2019.
Where is Michael Brennan located?
Michael Brennan practices at 1620 W Harrison St, Chicago, IL 60612. The listed phone number is (312) 942-5000.
What is Michael Brennan's specialty?
The primary specialty registered for this NPI is Internal Medicine, specializing in Critical Care Medicine, with taxonomy code 207RC0200X.
Is Michael Brennan enrolled in Medicare?
Yes. Michael Brennan is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.
Which organizations bill Medicare for Michael Brennan's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Michael Brennan reassigns Medicare benefits to 11 organizations: Rush University Medical Group (Chicago, IL), Rush Medical Group (Chicago, IL), Cepamerica Illinois LLP (Chicago, IL), St Anthony Emergency Services Physician Group (Chicago, IL), Advocate Health & Hospitals Corp. (Chicago, IL) and 6 more organizations, listed in the Medicare section above. Each reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Michael Brennan's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
What insurance does Michael Brennan accept?
Health plans from Oscar Health, Priority Health and Wellmark Health Plan of Iowa, Inc. list Michael Brennan as in-network in at least one marketplace plan. Coverage varies by plan and year; verify with the insurer or the provider before a visit.
Is Michael Brennan affiliated with any hospitals?
According to CMS data, Michael Brennan is affiliated with Advocate Trinity Hospital, Rush Oak Park Hospital and Advocate Christ Hospital & Medical Center.
When was this NPI record last updated?
The NPPES record for Michael Brennan was last updated on September 24, 2025. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 13 months ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.
# Dr. Michael James Brennan, DO, MPH · NPI 1811550981
Critical Care Medicine physician in Chicago, Illinois. Individual provider, active in the CMS NPPES registry since April 15, 2019.
## Identity
- **NPI:** 1811550981 (Entity type: Individual)
- **Enumerated:** April 15, 2019
- **Primary specialty:** Internal Medicine - Critical Care Medicine · taxonomy 207RC0200X
- **State license:** 036.164300 (Illinois)
- **Sole proprietor:** No
## Practice location
- **Address:** 1620 W HARRISON ST, Chicago, IL 60612-3801
- **Phone:** (312) 942-5000
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 11 organizations under Medicare reassignment (form CMS-855R): Rush University Medical Group (NPI 1093819542, Chicago, IL); Rush Medical Group (NPI 1467312850, Chicago, IL); Cepamerica Illinois LLP (NPI 1265954465, Chicago, IL); St Anthony Emergency Services Physician Group (NPI 1760587703, Chicago, IL); Advocate Health & Hospitals Corp. (NPI 1750315545, Chicago, IL); and 6 more · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** Lake Erie Col Of Osteopathic Medicine, Bradenton, class of 2019
## Record status
- **NPPES last updated:** September 24, 2025
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Source: [NPI Profile](https://npiprofile.com/npi/1811550981) · Data from the CMS NPPES public registry.