Casey Ren, MD
Internal Medicine Physician · Stanford, CA
Casey Ren, MD is an internal medicine physician with a practice address in Stanford, California, and NPI 1447888003, issued on Mar 30, 2020. Check the license (California A185349, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Casey Ren
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- A185349 CA
Self-reported in NPPES; status is on the state search - Practice location
- 300 Pasteur Dr, Stanford, CA 94305
- Phone
- (650) 723-4000
- Enumerated
- Mar 30, 2020
- Record last updated
- Apr 23, 2024
- Medicare enrollment
- Enrolled (PECOS I20230705002703); accepts Medicare assignment
- Entity
- Type 1 · individual
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Verify Casey Ren in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A185349Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
98% fewer Medicare Part D claims than the average internal medicine physician in 2024
48 Medicare Part D claims for 21 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 27% of 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.
One hospital affiliation
- Stanford Health CareStanford, CA · Acute Care Hospitals5 of 5 stars
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through); hospitals matched to CMS Hospital General Information (Care Compare) (data.cms.gov). Star ratings are CMS hospital ratings, not ratings of this provider.
Casey Ren among 17,696 internal medicine physician records in California
Casey Ren, MD 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 2020, is newer than 89% of them.
- NPI issued2020 · 89% of these records are older, 8% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated2020 · median 2004 among the 11,065 with a school on file
- Record last updated2024 · 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).
378 internal medicine physician records list a practice address in Stanford
They are 378 of the 5,606 NPPES records with a practice address in Stanford, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in Stanford → Internal Medicine Physician nationwide →
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Common questions
What is Casey Ren, MD's NPI number?
Casey Ren, MD's National Provider Identifier (NPI) is 1447888003, issued on Mar 30, 2020. An NPI identifies a provider in billing; it is not a license.
Where is Casey Ren, MD located?
The NPPES record lists a practice address at 300 Pasteur Dr, Stanford, CA, 94305. Phone: (650) 723-4000. Providers update this record themselves, so call before visiting.
How can I verify Casey Ren, MD's license?
NPPES lists California license number A185349, 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 Casey Ren, MD prescribe under Medicare Part D?
In 2024, Casey Ren, MD had 48 Medicare Part D claims for 21 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.