Derek Way-Jun Shek, M.D.
Internal Medicine Physician · San Leandro, CA
Derek Way-Jun Shek, M.D. is an internal medicine physician with a practice address in San Leandro, California, and NPI 1154448587, issued on Mar 22, 2007. Check the license (California A95144, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Derek Way-Jun Shek
- Credential
- M.D.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- A95144 CA
Self-reported in NPPES; status is on the state search - Practice location
- 2500 Merced Street, San Leandro, CA 94577
- Phone
- (510) 454-1000
- Enumerated
- Mar 22, 2007
- Record last updated
- Feb 11, 2022
- Medicare enrollment
- Enrolled (PECOS I20080207000617); accepts Medicare assignment
- Medical or professional school
- Northwestern University Feinberg Medical School, 2004
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 17,696 in California → Look up another NPI →
Also registered at 2500 Merced Street
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Brian Au, PHARM DPharmacist1497803670
- Jacob Bayani, C.R.N.ACertified Registered Nurse Anesthetist1285690446
- Mary Ann Bloyer, C.N.M.Advanced Practice Midwife1003952276
- Jungsuk Byun, PHARMPharmacist1174675029
- Linda Chang, PHARM DPharmacist1629126826
- Chunting Chuang, PHARM DPharmacist1134394018
Verify Derek Way-Jun Shek in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A95144Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
7% fewer Medicare Part D claims than the average internal medicine physician in 2024
2,961 Medicare Part D claims for 360 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. 130 claims were for opioids.
Most prescribed
- Prednisone555 claims
- Abiraterone Acetate531 claims
- Tagrisso198 claims
- Dexamethasone167 claims
- Xtandi96 claims
- Olanzapine86 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.
Bills Medicare through one group practice
- Permanente Medical Group IncSan Leandro, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Derek Way-Jun Shek among 17,696 internal medicine physician records in California
Derek Way-Jun Shek, M.D. is one of 17,696 internal medicine physician records with a practice address in California. 79% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2007, is newer than 44% of them.
- NPI issued2007 · 44% of these records are older, 44% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated2004 · median 2004 among the 11,065 with a school on file
- Record last updated2022 · 61% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
62 internal medicine physician records list a practice address in San Leandro
They are 62 of the 4,976 NPPES records with a practice address in San Leandro, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in San Leandro → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Abhijan Banerjee, M.D.San Leandro, CA 945771548292113
- Leo Chi, M.D.San Leandro, CA 945771467530220
- Young Choi, D.O.San Leandro, CA 945771871671628
- Christian Dang, M.D.San Leandro, CA 945771417986753
- Louis Edelson, M.D.San Leandro, CA 945771356429120
- Mei Kung, M.D.San Leandro, CA 945771407939465
- Sandeep Lal, M.D.San Leandro, CA 945771558448340
- Evelyn Nakagawa, M.D.San Leandro, CA 945771023077294
Common questions
What is Derek Way-Jun Shek, M.D.'s NPI number?
Derek Way-Jun Shek, M.D.'s National Provider Identifier (NPI) is 1154448587, issued on Mar 22, 2007. An NPI identifies a provider in billing; it is not a license.
Where is Derek Way-Jun Shek, M.D. located?
The NPPES record lists a practice address at 2500 Merced Street, San Leandro, CA, 94577. Phone: (510) 454-1000. Providers update this record themselves, so call before visiting.
How can I verify Derek Way-Jun Shek, M.D.'s license?
NPPES lists California license number A95144, 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 Derek Way-Jun Shek, M.D. prescribe under Medicare Part D?
In 2024, Derek Way-Jun Shek, M.D. had 2,961 Medicare Part D claims for 360 beneficiaries; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
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.