Quick answers
- Which hospitals does Gretta M. Colby work at?
- Medicare's official clinician data lists Gretta M. Colby at 1 hospital: Aurora St Lukes Medical Center. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Gretta M. Colby see patients?
- Medicare's clinician data lists 2 practice locations, including Milwaukee, WI. Call before your visit to confirm the address.
- What is Gretta M. Colby's specialty?
- Medicare lists Internal Medicine as the primary specialty.
- Does Gretta M. Colby accept Medicare assignment?
- Yes. Medicare's clinician data says Gretta M. Colby 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 Gretta M. Colby?
- (414) 385-8600, as listed in official Medicare / NPI Registry data.
- What is Gretta M. Colby's NPI number?
- 1306587639. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Gretta M. Colby works
Medicare's Facility Affiliation Data lists Gretta M. Colby at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Aurora St Lukes Medical CenterMilwaukee, WI · Acute Care Hospital · CCN 520138
Practice locations
Addresses where Gretta M. Colby is enrolled with Medicare (CMS data updated 2026-10-02).
- 2801 W Kinnickinnic River PkwyMilwaukee, WI 53215 (414) 385‑8600
- 945 N 12th StMilwaukee, WI 53233 (414) 219‑7300
Group practices
Medicare enrollment lists Gretta M. Colby as a member of this group (CMS data updated 2026-10-02).
- Aurora Medical Group, Inc.3,813 clinicians in the group
Specialties
- Internal Medicineprimary
Other internal medicine doctors in Milwaukee
Clinicians with the same Medicare primary specialty in Milwaukee, WI — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Medical College Of Wisconsin |
| Graduation year | 2022 |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1306587639 |
| 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