Quick answers
- Does Gregory M. Keelen accept Medicare assignment?
- Yes. Medicare's clinician data says Gregory M. Keelen accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Gregory M. Keelen see?
- In 2024, CMS data shows 651 Original Medicare patients and 749 services for Gregory M. Keelen. This counts Original Medicare only and measures volume, not quality.
- What is Gregory M. Keelen's NPI number?
- 1811905227. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Gregory M. Keelen, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 651 |
|---|---|
| Services billed to Medicare | 749 |
| Different services or procedures | 28 |
| Participating Medicare provider | Yes |
| Average age of these patients | 75 |
Most frequent services
- Emergency department visit with high level of medical decision making (99285)334 services
- Emergency department visit with moderate level of medical decision making (99284)233 services
- Critical care, first 30-74 minutes (99291)104 services
- Routine electrocardiogram (ecg) using at least 12 leads with interpretation and report only (93010)18 services
- Emergency department visit with low level of medical decision making (99283)13 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High blood pressure75%
- High cholesterol75%
- Arthritis64%
- Ischemic heart disease47%
- Anxiety40%
- Diabetes38%
Hospitals where Gregory M. Keelen works
Medicare's Facility Affiliation Data lists Gregory M. Keelen at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- Saint Francis Hospital MuskogeeMuskogee, OK · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 370025
- Saint Francis Hospital South, LLCTulsa, OK · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 370218
- Saint Francis Hospital, IncTulsa, OK · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 370091
- Texoma Medical CenterDenison, TX · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 450324
Practice locations
Addresses where Gregory M. Keelen is enrolled with Medicare (CMS data updated October 2, 2026).
- 2710 W Hackberry LnAnna, TX 75409 (214) 831‑2600
- 4226 N US Hwy 75Sherman, TX 75090 (903) 487‑0857
- 5016 S US Hwy 75Denison, TX 75020 (903) 416‑4000
Group practices
Medicare enrollment lists Gregory M. Keelen as a member of these groups (CMS data updated October 2, 2026).
- Ies Central Texas PLLC34 clinicians in the group
- Level One Emergency Physicians LLC29 clinicians in the group
Specialties
- Emergency Medicineprimary
Other emergency medicine doctors in Anna
Clinicians with the same Medicare primary specialty in Anna, TX — not a recommendation.
Other clinicians in Ies Central Texas PLLC
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Kansas School Of Med (kc/wich/sal) |
| Graduation year | 2003 (23 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1811905227 |
| 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 October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- 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