Quick answers
- Which hospitals does Jason E. Grennan work at?
- Medicare's official clinician data lists Jason E. Grennan at 5 hospitals: Chickasaw Nation Medical Center, Mercy Health St Ritas Medical Center, Mercy Medical Center - Cedar Rapids, Southeast Iowa Regional Medical Center and UnityPoint Health - Marshalltown. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Jason E. Grennan see patients?
- Medicare's clinician data lists 30 practice locations, including Milford, MA, Gibson City, IL and Worcester, MA. Call before your visit to confirm the address.
- What is Jason E. Grennan's specialty?
- Medicare lists Diagnostic Radiology as the primary specialty.
- Does Jason E. Grennan accept Medicare assignment?
- Medicare's clinician data says Jason E. Grennan may accept Medicare assignment (as of 2026-10-02). Ask the office whether they accept it for your visit.
- What is the phone number for Jason E. Grennan?
- (508) 634-3100, as listed in official Medicare / NPI Registry data.
- What is Jason E. Grennan's NPI number?
- 1457313314. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Jason E. Grennan works
Medicare's Facility Affiliation Data lists Jason E. Grennan at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Chickasaw Nation Medical CenterAda, OK · Acute Care Hospital · CCN 370180
- Mercy Health St Ritas Medical CenterLima, OH · Acute Care Hospital · CCN 360066
- Mercy Medical Center - Cedar RapidsCedar Rapids, IA · Acute Care Hospital · CCN 160079
- Southeast Iowa Regional Medical CenterWest Burlington, IA · Acute Care Hospital · CCN 160057
- UnityPoint Health - MarshalltownMarshalltown, IA · Acute Care Hospital · CCN 160001
Practice locations
Addresses where Jason E. Grennan is enrolled with Medicare (CMS data updated 2026-10-02). The first 5 of 30; the Medicare profile lists all.
- 101 Cedar StMilford, MA 01757 (508) 634‑3100
- 1120 N Melvin StGibson City, IL 60936 · Gibson Community Hospital Association (217) 784‑4251
- 123 Summer StWorcester, MA 01608 (508) 363‑5000
- 1400 Worcester StNatick, MA 01760 (508) 595‑2700
- 1401 W 5th StSheridan, WY 82801 · Memorial Hospital of Sheridan County (307) 672‑1000
Group practices
Medicare enrollment lists Jason E. Grennan as a member of these groups (CMS data updated 2026-10-02).
- The Duluth Clinic Ltd1,144 clinicians in the group
- Avera McKennan959 clinicians in the group
- Reliant Medical Group Inc640 clinicians in the group
- McFarland Clinic PC363 clinicians in the group
- Hannibal Regional Healthcare System Inc272 clinicians in the group
- Southeast Iowa Regional Medical Center Inc259 clinicians in the group
Specialties
- Diagnostic Radiologyprimary
Other radiologists in Milford
Clinicians with the same Medicare primary specialty in Milford, MA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Nebraska College Of Medicine |
| Graduation year | 1999 |
| Gender (as listed) | Male |
| Medicare assignment | May accept for some services |
| NPI (National Provider Identifier) | 1457313314 |
| 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