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Edit this profileAt a glance
- 101 E Valencia Mesa Dr, Fullerton, CA 92835
About Dr. Yoon
Based in Fullerton, CA, Stephen Yoon, M.D. is listed in the NPI registry under internal medicine. Stephen graduated from Rutgers New Jersey Medical School in 1998. According to Medicare claims data, Stephen cared for 460 Medicare patients across 663 services. The services billed most often include subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes, subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes, and hospital discharge day management, more than 30 minutes. NPI 1851327100 identifies this record in the national registry.
Factual summary compiled by Guide.md from public records; not written by this provider.
Education & Training
Specialty
Credentials & Licensing
Medicare information
Exactly as CMS reports it (National Downloadable File, Opt-Out Affidavits, Order & Referring). Not an insurance directory; confirm coverage with the office.
Contact Information
- (714) 992-3000
- Email not available
Practice Locations
101 E VALENCIA MESA DR
Fullerton, CA 92835
Conditions Commonly Evaluated or Treated
Within Internal Medicine generally. Availability varies by clinician, training and location — this profile has not been claimed, so nothing here is a personal claim by the provider.
Conditions
Cancer Prevention
Cancer risk
Environmental health
- Asbestos Exposure
- Contaminated drinking water exposure
- Heat exhaustion and heat stroke
- Radon gas exposure
- Tick bite and Lyme disease risk
- Toxic Mold Exposure
- Wildfire smoke and air pollution exposure
- Workplace Chemical Exposure
General wellness
Heart health
Infectious Disease
Infectious disease
Kidney health
Lifestyle & wellness
Lifestyle health
Longevity
Metabolic & Lifestyle
Occupational health
Occupational Health
Rashes & allergy
Sexual Health
Sexual health
Substance use
Travel health
Wellness and energy
Workplace health
Most searched conditions
Cardiometabolic
Digestive and liver
Endocrine, blood, and bone
Kidney and urinary
Respiratory
Blood & Circulation
Blood disorders
Brain & Nerves
Brain and nerves
Cardiac and vascular
Digestive
Heart & Circulation
Infections
Kidney & Bladder
Lungs & Breathing
Mental Health
Neurologic and behavioral
Pain
Rheumatologic and pain
Procedures & services
Addiction & habits
Cancer screening
Cancer Screening
Checkups & exams
Chronic illness
Diagnostics & screening
Environmental health
Fitness & body composition
Heart & Circulation
Heart & circulation
Heart health
Hospital-based procedures
Imaging referral
Immunizations
Infection & Microbiology Tests
Lifestyle & Prevention
Longevity
Lower endoscopy
Lungs & Breathing
Metabolic & Weight
Metabolic health
Occupational health
Occupational Health
Office Procedures
Preventive and evaluation
- Preoperative medical clearance
- Medication management
- Post-hospital transitional care
Preventive imaging
Preventive screening
Routine Blood Tests
Screening & labs
Screening and diagnostic testing
- Blood pressure screening
- Cancer screening and prevention planning
- Diabetes and prediabetes screening
- EKG
- Spirometry
Screenings & Diagnostics
Travel Health
Travel medicine
Wellness
Wellness & Screening
Workplace health
Skin growths
Sleep
Most searched procedures
Bones & Joints
Brain and nerves
Digestive
Exams & Consultations
Lab tests
Minor procedures
Office procedures
Pain management
Preventive & Routine Care
Sexual health
Procedures Most Often Billed to Medicare
663 services · 460 patients · 6 distinct codes
| Procedure | Type | Code | Services | Compared with peers |
|---|---|---|---|---|
| Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes | Office visit | 99233 |
228 | More often than most peers in Internal Medicine |
| Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes | Office visit | 99232 |
222 | More often than most peers in Internal Medicine |
| Hospital discharge day management, more than 30 minutes | Office visit | 99239 |
114 | More often than most peers in Internal Medicine |
| Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes | Office visit | 99222 |
50 | More often than most peers in Internal Medicine |
| Hospital discharge day management, 30 minutes or less | Office visit | 99238 |
30 | As often as other peers in Internal Medicine |
| Subsequent hospital care with straightforward or low level of medical decision making, per day, if using time, at least 25 minutes | Office visit | 99231 |
19 | Less often than most peers in Internal Medicine |
Source: CMS Medicare public data. Shows how often procedures were billed — not quality of care or patient satisfaction.
Related providers
Connections drawn from the registry and from what providers have told us. A link here is not a referral or an endorsement.
Other internists at this location 7
Same specialty, same street address — most likely the same department or group.
Related specialists at this location 7
Clinically related specialties at the same address — the people this provider most likely works alongside.
Also at this address 4
Providers at the same street address. Each files their own registry entry, so a shared practice often appears under several different names.
More connections — 22 related providers in 3 groups
Other internists in Fullerton 6
Same specialty, same city.
Trained at Rutgers New Jersey Medical School 8
Other providers in the same specialty who trained at the same institution.
Class of 1998 at Rutgers New Jersey Medical School 8
Providers who graduated from the same medical school in the same year.
Common questions
What does Stephen Yoon specialize in?
Stephen Yoon is an internist in Fullerton, CA. That is the designation recorded for this NPI in the federal registry, where it is listed as “Internal Medicine”.
NPI registry
Where is Stephen Yoon located?
Stephen Yoon is listed at 101 E Valencia Mesa Dr, Fullerton, CA 92835. Addresses come from the NPI registry and can lag a move, so confirm before travelling.
NPI registry
What is Stephen Yoon's phone number?
The number on file is (714) 992-3000. Contact the office directly to confirm availability and scheduling.
NPI registry
What is Stephen Yoon's NPI number?
Stephen Yoon's National Provider Identifier is 1851327100. It is issued by the Centers for Medicare & Medicaid Services and is unique and permanent — it does not change if they move practice.
NPI registry
Where did Stephen Yoon train?
Stephen Yoon attended Rutgers New Jersey Medical School, graduating in 1998. This comes from the CMS National Downloadable File.
CMS public data
How long has Stephen Yoon been practicing?
Stephen Yoon has 28 years experience. Calculated from a graduation year of 1998, reported in the CMS National Downloadable File.
CMS public data
What does Stephen Yoon do most often?
According to Medicare billing data, Stephen Yoon the Medicare record under this individual NPI shows mainly office visits and diagnostic testing. Hospital-based physicians usually have their procedural work billed by the facility rather than under their own number, so this is a floor on their practice, not a description of it. This reflects Medicare patients only and is billing volume, not a measure of quality.
Medicare claims
Has Stephen Yoon confirmed this information?
Not yet. This profile is built from public federal data and has not been confirmed by Stephen Yoon. If this is you, claiming it is free.
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Guide.md listings do not constitute medical advice or an endorsement.