Mark John Castellanet, M.D.
Cardiovascular Disease Physician · Los Alamitos, CA
Mark John Castellanet, M.D. is a cardiovascular disease physician with a practice address in Los Alamitos, California, and NPI 1538165782, issued on Jun 22, 2005. Check the license (California GZ8642, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Mark John Castellanet
- Credential
- M.D.
- Primary taxonomy
- Cardiovascular Disease Physician 207RC0000X
- License number
- GZ8642 CA
Self-reported in NPPES; status is on the state search - Practice location
- 3801 Katella Ave, Los Alamitos, CA 90720
- Phone
- (562) 598-3200
- Enumerated
- Jun 22, 2005
- Record last updated
- Jul 13, 2026
- Fax
- (562) 799-3646
- Medicaid ID
- 00GZ86420 CA
- Entity
- Type 1 · individual
8 nearest cardiovascular disease physician records → All 2,574 in California → Look up another NPI →
Also registered at 3801 Katella Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Mark John Castellanet in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license GZ8642Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
99% fewer Medicare Part D claims than the average cardiovascular disease physician in 2024
39 Medicare Part D claims, against an average of 3,078 among the 20,728 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.
Mark John Castellanet among 2,574 cardiovascular disease physician records in California
Mark John Castellanet, M.D. is one of 2,574 cardiovascular disease 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 2005, is newer than 0% of them.
- NPI issued2005 · 0% of these records are older, 90% newer
- In a Medicare fileYes · 83% of these records are
- In the CMS Doctors and Clinicians fileNo · 68% of these records are
- Record last updated2026 · 63% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RC0000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Cardiovascular Disease Physician providers in California
There are 2,574 cardiovascular disease physician records in California.
All 2,574 in California → Every provider in Los Alamitos → Cardiovascular Disease Physician nationwide →
The 8 cardiovascular disease physician records with the nearest ZIP codes
- Ramandeep Brar, M.D.Los Alamitos, CA 907201821165549
- Stuart Fischer, M.D.Los Alamitos, CA 907201083656086
- Steven Forman, M.D.Los Alamitos, CA 907201023059763
- Diana GlovaciLos Alamitos, CA 907201366805590
- Fernando Mendoza, M.D.Los Alamitos, CA 907201063637320
- Timothy O'Neill, M.D.Los Alamitos, CA 907201467493155
- Adrian Shandling, MDLos Alamitos, CA 907201386640522
- Bret Witter, M.D.Los Alamitos, CA 907201396783387
Common questions
What is Mark John Castellanet, M.D.'s NPI number?
Mark John Castellanet, M.D.'s National Provider Identifier (NPI) is 1538165782, issued on Jun 22, 2005. An NPI identifies a provider in billing; it is not a license.
Where is Mark John Castellanet, M.D. located?
The NPPES record lists a practice address at 3801 Katella Ave, Los Alamitos, CA, 90720. Phone: (562) 598-3200. Providers update this record themselves, so call before visiting.
How can I verify Mark John Castellanet, M.D.'s license?
NPPES lists California license number GZ8642, 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 Mark John Castellanet, M.D. prescribe under Medicare Part D?
In 2024, Mark John Castellanet, M.D. had 39 Medicare Part D claims; the average among cardiovascular disease physician prescribers was 3,078. 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.