Chester D. Zahn, MD
Gastroenterology Physician · San Gabriel, CA
Chester D. Zahn, MD is a gastroenterology physician with a practice address in San Gabriel, California, and NPI 1639146442, issued on Mar 1, 2006. Check the license (California G69510, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Chester D. Zahn
- Credential
- MD
- Primary taxonomy
- Gastroenterology Physician 207RG0100X
- License number
- G69510 CA
Self-reported in NPPES; status is on the state search - Practice location
- 1026 E Las Tunas Dr, San Gabriel, CA 91776
- Phone
- (626) 287-7222
- Enumerated
- Mar 1, 2006
- Record last updated
- Mar 20, 2020 (not updated in 6 years: call before relying on the address or phone)
- Fax
- (626) 287-1991
- Medicaid ID
- 00G695100 CA
- Medicare enrollment
- Enrolled (PECOS I20070313000649); accepts Medicare assignment
- Medical or professional school
- Stanford University School Of Medicine, 1983
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest gastroenterology physician records → All 2,140 in California → Look up another NPI →
Verify Chester D. Zahn in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G69510Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
4.0 times the Medicare Part D claims of the average gastroenterology physician in 2024
3,267 Medicare Part D claims for 681 beneficiaries, against an average of 811 among the 16,445 providers of this specialty who prescribed in Part D. Brand-name drugs were 5% of claims.
Most prescribed
- Bethanechol Chloride1,180 claims
- Omeprazole622 claims
- Isosorbide Mononitrate Er208 claims
- Gavilyte-G167 claims
- Entecavir110 claims
- Ursodiol89 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
The MIPS final score for 2023 (Medicare payment program): 40.8 of 100
The Merit-based Incentive Payment System score is reported for this clinician. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023; category weights for 2023 (qpp.cms.gov).
Industry payments in 2024: $296.06
17 payments; by number, the most common kind was food and beverage; the largest payer was Gilead Sciences, Inc. The 13,350 providers of this specialty with any payment received $5,015.95 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Chester D. Zahn among 2,140 gastroenterology physician records in California
Chester D. Zahn, MD is one of 2,140 gastroenterology physician records with a practice address in California. 83% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 7% of them.
- NPI issued2006 · 7% of these records are older, 48% newer
- In a Medicare fileYes · 83% of these records are
- In the CMS Doctors and Clinicians fileYes · 72% of these records are
- Graduated1983 · median 2002 among the 1,538 with a school on file
- Record last updated2020 · 60% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RG0100X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Gastroenterology Physician providers in California
There are 2,140 gastroenterology physician records in California.
All 2,140 in California → Every provider in San Gabriel → Gastroenterology Physician nationwide →
The 8 gastroenterology physician records with the nearest ZIP codes
- Robert Mehler, M.D.San Gabriel, CA 917761730259243
- Dana Pan, MDSan Gabriel, CA 917761265842934
- Tien-Chun Chen, MDTemple City, CA 917801396005450
- Ken Nguyen, M.D.Temple City, CA 917801205193828
- Steve Nguyen, D.O.Rosemead, CA 917701649357732
- Tu Tranvan, M.D.Rosemead, CA 917701376570184
- Andrew Dam, DOPomona, CA 917671225590037
- Gerald Goldman, MDPomona, CA 917671538232905
Common questions
What is Chester D. Zahn, MD's NPI number?
Chester D. Zahn, MD's National Provider Identifier (NPI) is 1639146442, issued on Mar 1, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Chester D. Zahn, MD located?
The NPPES record lists a practice address at 1026 E Las Tunas Dr, San Gabriel, CA, 91776. Phone: (626) 287-7222. Providers update this record themselves, so call before visiting.
How can I verify Chester D. Zahn, MD's license?
NPPES lists California license number G69510, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Chester D. Zahn, MD prescribe under Medicare Part D?
In 2024, Chester D. Zahn, MD had 3,267 Medicare Part D claims for 681 beneficiaries; the average among gastroenterology physician prescribers was 811. Part D covers Medicare prescriptions only.
What is Chester D. Zahn, MD's MIPS final score?
The 2023 MIPS final score is 40.8 of 100. The average among 454,083 clinicians with a measured score was 83.5.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.