Mason Shieh, M.D., M.B.A.
Emergency Medicine Physician · Los Alamitos, CA
Mason Shieh, M.D., M.B.A. is an emergency medicine physician with a practice address in Los Alamitos, California, and NPI 1467718486, issued on Apr 3, 2012. Check the license (California A134394, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Mason Shieh
- Credential
- M.D., M.B.A.
- Primary taxonomy
- Emergency Medicine Physician 207P00000X
- License number
- A134394 CA
Self-reported in NPPES; status is on the state search - Practice location
- 3751 Katella Ave, Los Alamitos, CA 90720
- Phone
- (714) 456-8888
- Enumerated
- Apr 3, 2012
- Record last updated
- Apr 2, 2025
- Medicare enrollment
- Enrolled (PECOS I20150630002834); accepts Medicare assignment
- Medical or professional school
- University Of California, Irvine, California College Of Medicine, 2012
- Entity
- Type 1 · individual
8 nearest emergency medicine physician records → All 7,751 in California → Look up another NPI →
Also registered at 3751 Katella Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Moustafa Aboshady, M.D.Hospitalist Physician1003127655
- Denis Bolton, D.O.Diagnostic Radiology Physician1952493876
- George Bozeman, MDEmergency Medicine Physician1295771285
- Kirsten Calder, MDEmergency Medicine Physician1952330938
- Monica Choi, MDAnesthesiology Physician1578804506
- Benjamin Cowan, MDDiagnostic Radiology Physician1760465728
Verify Mason Shieh in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A134394Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
62% more Medicare Part D claims than the average emergency medicine physician in 2024
365 Medicare Part D claims for 230 beneficiaries, against an average of 226 among the 54,106 providers of this specialty who prescribed in Part D. 54 claims were for opioids.
Most prescribed
- Ondansetron Odt37 claims
- Cephalexin34 claims
- Hydrocodone-Acetaminophen28 claims
- Cefpodoxime Proxetil25 claims
- Amoxicillin-Clavulanate Potass19 claims
- Dicyclomine Hcl14 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 practice group's MIPS final score for 2023 (Medicare payment program): 94.6 of 100
The Merit-based Incentive Payment System score is reported for the practice group, not for one clinician alone. 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, group reporting; category weights for 2023 (qpp.cms.gov).
Bills Medicare through one group practice
- Cep America - CaliforniaGlendora, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Mason Shieh among 7,751 emergency medicine physician records in California
Mason Shieh, M.D., M.B.A. is one of 7,751 emergency medicine physician records with a practice address in California. 81% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2012, is newer than 63% of them.
- NPI issued2012 · 63% of these records are older, 34% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileYes · 59% of these records are
- Graduated2012 · median 2011 among the 4,560 with a school on file
- Record last updated2025 · 59% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207P00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
19 emergency medicine physician records list a practice address in Los Alamitos
They are 19 of the 1,035 NPPES records with a practice address in Los Alamitos, and 7,751 emergency medicine physician records in California.
All 7,751 in California → Every provider in Los Alamitos → Emergency Medicine Physician nationwide →
The 8 emergency medicine physician records with the nearest ZIP codes
- George Bozeman, MDLos Alamitos, CA 907201295771285
- Kirsten Calder, MDLos Alamitos, CA 907201952330938
- Monica Kumar, M.D,Los Alamitos, CA 907201700058963
- Mina Masri, D.O.Los Alamitos, CA 907201750390993
- Gregory Moreno, MDLos Alamitos, CA 907201245249481
- Michael Perlman, M.D.Los Alamitos, CA 907201144256355
- Charles Rennie, MDLos Alamitos, CA 907201295767523
- Ivan Rokos, MDLos Alamitos, CA 907201184681991
Common questions
What is Mason Shieh, M.D., M.B.A.'s NPI number?
Mason Shieh, M.D., M.B.A.'s National Provider Identifier (NPI) is 1467718486, issued on Apr 3, 2012. An NPI identifies a provider in billing; it is not a license.
Where is Mason Shieh, M.D., M.B.A. located?
The NPPES record lists a practice address at 3751 Katella Ave, Los Alamitos, CA, 90720. Phone: (714) 456-8888. Providers update this record themselves, so call before visiting.
How can I verify Mason Shieh, M.D., M.B.A.'s license?
NPPES lists California license number A134394, 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 Mason Shieh, M.D., M.B.A. prescribe under Medicare Part D?
In 2024, Mason Shieh, M.D., M.B.A. had 365 Medicare Part D claims for 230 beneficiaries; the average among emergency medicine physician prescribers was 226. Part D covers Medicare prescriptions only.
What is Mason Shieh, M.D., M.B.A.'s MIPS final score?
The 2023 MIPS final score is 94.6 of 100, reported for the practice group. 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.