Michael Terrence O'Brien, M.D.
Family Medicine Physician · Castro Valley, CA
Michael Terrence O'Brien, M.D. is a family medicine physician with a practice address in Castro Valley, California, and NPI 1821181215, issued on Sep 30, 2006. Check the license (California G61152, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Michael Terrence O'Brien
- Credential
- M.D.
- Primary taxonomy
- Family Medicine Physician 207Q00000X
- License number
- G61152 CA
Self-reported in NPPES; status is on the state search - Practice location
- 20100 Lake Chabot RD, Castro Valley, CA 94546
- Phone
- (510) 581-7677
- Enumerated
- Sep 30, 2006
- Record last updated
- Aug 21, 2007 (not updated in 19 years: call before relying on the address or phone)
- Entity
- Type 1 · individual
8 nearest family medicine physician records → All 17,133 in California → Look up another NPI →
Verify Michael Terrence O'Brien in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G61152Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
86% fewer Medicare Part D claims than the average family medicine physician in 2024
506 Medicare Part D claims for 66 beneficiaries, against an average of 3,544 among the 117,163 providers of this specialty who prescribed in Part D. Brand-name drugs were 10% of claims.
Most prescribed
- Atorvastatin Calcium34 claims
- Donepezil Hcl24 claims
- Allopurinol23 claims
- Memantine Hcl23 claims
- Tamsulosin Hcl21 claims
- Pantoprazole Sodium17 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.
Industry payments in 2024: $34.13
1 payment: food and beverage; the largest payer was Amgen Inc. The 55,478 providers of this specialty with any payment received $902.55 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Michael Terrence O'Brien among 17,133 family medicine physician records in California
Michael Terrence O'Brien, M.D. is one of 17,133 family 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 6% of them.
- NPI issued2006 · 6% of these records are older, 59% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileNo · 62% of these records are
- Record last updated2007 · 58% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207Q00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
22 family medicine physician records list a practice address in Castro Valley
They are 22 of the 999 NPPES records with a practice address in Castro Valley, and 17,133 family medicine physician records in California.
All 17,133 in California → Every provider in Castro Valley → Family Medicine Physician nationwide →
The 8 family medicine physician records with the nearest ZIP codes
- Ahmad Ayoubi, M.D., M.SCastro Valley, CA 945461992926075
- Huong Dang, MDCastro Valley, CA 945461417390071
- Elmer Jason Grande, MDCastro Valley, CA 945461235323007
- Peter Hein, MDCastro Valley, CA 945461497803282
- Bhoomika Kamath, M.D.Castro Valley, CA 945461295991354
- Jaya Karnani, MDCastro Valley, CA 945461457309783
- Genevieve King, M. D.Castro Valley, CA 945461861561243
- Christopher Moore, MDCastro Valley, CA 945461437417029
Common questions
What is Michael Terrence O'Brien, M.D.'s NPI number?
Michael Terrence O'Brien, M.D.'s National Provider Identifier (NPI) is 1821181215, issued on Sep 30, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Michael Terrence O'Brien, M.D. located?
The NPPES record lists a practice address at 20100 Lake Chabot RD, Castro Valley, CA, 94546. Phone: (510) 581-7677. Providers update this record themselves, so call before visiting.
How can I verify Michael Terrence O'Brien, M.D.'s license?
NPPES lists California license number G61152, 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 Terrence O'Brien, M.D. prescribe under Medicare Part D?
In 2024, Michael Terrence O'Brien, M.D. had 506 Medicare Part D claims for 66 beneficiaries; the average among family medicine physician prescribers was 3,544. 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.