Stephen Yoon, M.D.
NPI 1851327100 · Internal Medicine Physician · Fullerton, CA
Enrolled with Medicare as Practitioner - Internal Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Stephen Yoon, M.D. is a Internal Medicine Physician provider in Fullerton, CA (NPI 1851327100).
Provider details
- NPI number
- 1851327100
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- A71645 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
19 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
663 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 Moderate Levelof Medical Decision Making, If Using Time, at Least 50 Minutes99233 | 228 | $122 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 222 | $81 |
| Hospital Discharge Day Management, More Than 30 Minutes99239 | 114 | $119 |
| Initial Hospital Care With Straightforward Or Low-Level Medical Decision Making, If Using Time, at Least 55 Minutes99222 | 50 | $135 |
| Hospital Discharge Day Management, 30 Minutes Or Less99238 | 30 | $84 |
| Subsequent Hospital Care With Straightforward Or Low Level of Medical Decision Making, Per Day, If Using Time, at Least 25 Minutes99231 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 13 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Amoxicillin/Potassium Clavbrand: Amoxicillin-Clavulanate Potass | 43 | 43 |
| Pantoprazole Sodium | 29 | 18 |
| Furosemide | 29 | 22 |
| Atorvastatin Calcium | 27 | 19 |
| Prednisone | 21 | 19 |
| Clopidogrel Bisulfatebrand: Clopidogrel | 19 | — |
| Carvedilol |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$145 across 6 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
- 2006-06-25
- Last updated
- 2015-05-13
Frequently asked questions
- What is Stephen Yoon's NPI number?
- Stephen Yoon's National Provider Identifier (NPI) is 1851327100, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Stephen Yoon's specialty?
- Stephen Yoon is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Stephen Yoon located?
- Stephen Yoon's practice location on file with NPPES is 101 E Valencia Mesa Dr, Fullerton, CA 92835-3809.
- What is Stephen Yoon's phone number?
- The practice phone number listed in the NPPES registry for Stephen Yoon is (714) 992-3000.
- Does Stephen Yoon accept Medicare?
- Stephen Yoon is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Stephen Yoon's NPI active?
- Yes — Stephen Yoon's NPI (1851327100) is active in the NPPES registry as of the last update on 2015-05-13.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.