Chester Zahn, MD
NPI 1639146442 · Gastroenterology Physician · San Gabriel, CA
Enrolled with Medicare as Practitioner - Gastroenterology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Chester Zahn, MD is a Gastroenterology Physician provider in San Gabriel, CA (NPI 1639146442).
Provider details
- NPI number
- 1639146442
- Entity type
- Individual
- Primary specialty
- Gastroenterology PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- Yes
- License
- G69510 (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
20 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
2,761 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) |
|---|---|---|
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 705 | $98 |
| Initial Hospital Care With Straightforward Or Low-Level Medical Decision Making, If Using Time, at Least 55 Minutes99222 | 437 | $135 |
| Subsequent Hospital Care With Straightforward Or Low Level of Medical Decision Making, Per Day, If Using Time, at Least 25 Minutes99231 | 422 | $51 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 253 | $81 |
| Biopsy of Esophagus, Stomach, And/Or Upper Small Bowel Using a Flexible Endoscope43239 | 164 | $75 |
| New Patient Office Or Other Outpatient Visit With Moderate Level of Medical Decision Making, If Using Time, 45 Minutes Or More |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 29 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Bethanechol Chloride | 1,180 | 366 |
| Omeprazole | 622 | 186 |
| Isosorbide Mononitratebrand: Isosorbide Mononitrate Er | 208 | 62 |
| Peg3350/Sod Sulf,bicarb,cl/Kclbrand: Gavilyte-G | 167 | 164 |
| Entecavir | 110 | 16 |
| Ursodiol | 89 | 21 |
| Rosuvastatin Calcium | 87 | 28 |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$296 across 17 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
- 2006-03-01
- Last updated
- 2020-03-20
- Certified
- 2020-03-20
Frequently asked questions
- What is Chester Zahn's NPI number?
- Chester Zahn's National Provider Identifier (NPI) is 1639146442, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Chester Zahn's specialty?
- Chester Zahn is listed in the NPPES registry with a primary specialty of Gastroenterology Physician (Allopathic & Osteopathic Physicians).
- Where is Chester Zahn located?
- Chester Zahn's practice location on file with NPPES is 1026 E Las Tunas Dr, San Gabriel, CA 91776-1633.
- What is Chester Zahn's phone number?
- The practice phone number listed in the NPPES registry for Chester Zahn is (626) 287-7222.
- Does Chester Zahn accept Medicare?
- Chester Zahn is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Chester Zahn's NPI active?
- Yes — Chester Zahn's NPI (1639146442) is active in the NPPES registry as of the last update on 2020-03-20.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.