Ioannis Karkatzounis, MD
NPI 1639335235 · Hospitalist Physician · Oshkosh, WI
Enrolled with Medicare as Practitioner - Hospitalist · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Ioannis Karkatzounis, MD is a Hospitalist Physician provider in Oshkosh, WI (NPI 1639335235).
Provider details
- NPI number
- 1639335235
- Entity type
- Individual
- Primary specialty
- Hospitalist PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- Yes
- License
- 2960 (WI)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
17 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
940 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our .
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Subsequent Hospital Care With Straightforward Or Low Level of Medical Decision Making, Per Day, If Using Time, at Least 25 Minutes99231 | 357 | $47 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 291 | $76 |
| Initial Hospital Care With Straightforward Or Low-Level Medical Decision Making, If Using Time, at Least 55 Minutes99222 | 121 | $126 |
| Hospital Discharge Day Management, 30 Minutes Or Less99238 | 89 | $76 |
| Hospital Discharge Day Management, More Than 30 Minutes99239 | 54 | $110 |
| Initial Hospital Care With Straightforward Or Low Level of Medical Decision Making, Per Day, If Using Time, at Least 40 Minutes99221 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 9 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Prednisone | 27 | 26 |
| Amlodipine Besylate | 25 | 19 |
| Atorvastatin Calcium | 24 | 12 |
| Cefuroxime Axetilbrand: Cefuroxime | 24 | 23 |
| Pantoprazole Sodium | 22 | 18 |
| Clopidogrel Bisulfatebrand: Clopidogrel | 22 | — |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$293 across 7 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Registry dates
- Enumerated
- 2008-08-03
- Last updated
- 2024-09-26
- Certified
- 2024-09-26
Frequently asked questions
- What is Ioannis Karkatzounis's NPI number?
- Ioannis Karkatzounis's National Provider Identifier (NPI) is 1639335235, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Ioannis Karkatzounis's specialty?
- Ioannis Karkatzounis is listed in the NPPES registry with a primary specialty of Hospitalist Physician (Allopathic & Osteopathic Physicians).
- Where is Ioannis Karkatzounis located?
- Ioannis Karkatzounis's practice location on file with NPPES is 855 N Westhaven Dr, Oshkosh, WI 54904-7668.
- What is Ioannis Karkatzounis's phone number?
- The practice phone number listed in the NPPES registry for Ioannis Karkatzounis is (920) 303-8700.
- Does Ioannis Karkatzounis accept Medicare?
- Ioannis Karkatzounis is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Ioannis Karkatzounis's NPI active?
- Yes — Ioannis Karkatzounis's NPI (1639335235) is active in the NPPES registry as of the last update on 2024-09-26.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.