Michael Warren Nielsen, MD
Emergency Medicine Physician · San Diego, CA
Michael Warren Nielsen, MD is an emergency medicine physician with a practice address in San Diego, California, and NPI 1255301370, issued on Jan 23, 2006. Check the license (California A79412, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Michael Warren Nielsen
- Credential
- MD
- Primary taxonomy
- Emergency Medicine Physician 207P00000X
- License number
- A79412 CA
Self-reported in NPPES; status is on the state search - Practice location
- 200 W Arbor Dr, San Diego, CA 92103
- Phone
- (619) 543-6236
- Enumerated
- Jan 23, 2006
- Record last updated
- Feb 4, 2010 (not updated in 16 years: call before relying on the address or phone)
- Medicaid IDs
- 1255301370 CA
00A7941206141 CA - Entity
- Type 1 · individual
8 nearest emergency medicine physician records → All 7,751 in California → Look up another NPI →
Also registered at 200 W Arbor Dr
A shared address usually means a shared clinic or building; it does not show who employs whom.
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- Paula Abeleda, NPFamily Nurse Practitioner1558945022
Verify Michael Warren Nielsen in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A79412Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
92% fewer Medicare Part D claims than the average emergency medicine physician in 2024
18 Medicare Part D claims, against an average of 226 among the 54,106 providers of this specialty who prescribed in Part D.
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.
Michael Warren Nielsen among 7,751 emergency medicine physician records in California
Michael Warren Nielsen, MD 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 2006, is newer than 4% of them.
- NPI issued2006 · 4% of these records are older, 60% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileNo · 59% of these records are
- Record last updated2010 · 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).
Emergency Medicine Physician providers in California
There are 7,751 emergency medicine physician records in California.
All 7,751 in California → Every provider in San Diego → Emergency Medicine Physician nationwide →
The 8 emergency medicine physician records with the nearest ZIP codes
- Carolyn Barber, MDSan Diego, CA 921031750325502
- Anthony Bielawski, M.D.San Diego, CA 921031528038346
- Colleen Campbell, MDSan Diego, CA 921031669416483
- Richard Childers, M.D.San Diego, CA 921031902876220
- Michelle Daniel, MDSan Diego, CA 921031801879861
- Julian Lis, M.D.San Diego, CA 921031932100062
- Leslie Mukau, MDSan Diego, CA 921031578526026
- Sassan Naderi, M.D.San Diego, CA 921031811987936
Common questions
What is Michael Warren Nielsen, MD's NPI number?
Michael Warren Nielsen, MD's National Provider Identifier (NPI) is 1255301370, issued on Jan 23, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Michael Warren Nielsen, MD located?
The NPPES record lists a practice address at 200 W Arbor Dr, San Diego, CA, 92103. Phone: (619) 543-6236. Providers update this record themselves, so call before visiting.
How can I verify Michael Warren Nielsen, MD's license?
NPPES lists California license number A79412, 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 Michael Warren Nielsen, MD prescribe under Medicare Part D?
In 2024, Michael Warren Nielsen, MD had 18 Medicare Part D claims; the average among emergency medicine physician prescribers was 226. 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.