Mark Stephen Singer, M.D.
Internal Medicine Physician · Napa, CA
Mark Stephen Singer, M.D. is an internal medicine physician with a practice address in Napa, California, and NPI 1962486332, issued on Nov 30, 2005. Check the license (California G53924, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Mark Stephen Singer
- Credential
- M.D.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License numbers
- G53924 CA
CAG539243 CA
Self-reported in NPPES; status is on the state search - Practice location
- 3334 Sterling CT, Napa, CA 94558
- Phone
- (707) 365-5151
- Enumerated
- Nov 30, 2005
- Record last updated
- Jul 12, 2010 (not updated in 16 years: call before relying on the address or phone)
- Fax
- (707) 252-4887
- Medicare enrollment
- Enrolled (PECOS I20040920001187); accepts Medicare assignment
- Medical or professional school
- University Of California, Geffen School Of Medicine, 1983
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 17,696 in California → Look up another NPI →
Verify Mark Stephen Singer in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G53924Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
8% more Medicare Part D claims than the average internal medicine physician in 2024
3,444 Medicare Part D claims for 160 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. 142 claims were for opioids.
Most prescribed
- Levothyroxine Sodium220 claims
- Eliquis171 claims
- Atorvastatin Calcium142 claims
- Gabapentin107 claims
- Trazodone Hcl106 claims
- Furosemide98 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.
Mark Stephen Singer among 17,696 internal medicine physician records in California
Mark Stephen Singer, 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 2005, is newer than 0% of them.
- NPI issued2005 · 0% of these records are older, 95% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated1983 · median 2004 among the 11,065 with a school on file
- Record last updated2010 · 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).
61 internal medicine physician records list a practice address in Napa
They are 61 of the 3,583 NPPES records with a practice address in Napa, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in Napa → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Abhijit Adhye, M.D.Napa, CA 945581992763205
- Scott Anderson, MDNapa, CA 945581619929494
- Patricia Dizmang, M.D.Napa, CA 945581194790261
- Beth Hartung, M.D.Napa, CA 945581275501488
- Ronald Julis, M.D.Napa, CA 945581053311167
- Paul Laband, MDNapa, CA 945581427029040
- Monica McKeever, MDNapa, CA 945581538135298
- Lane Melgarejo, MDNapa, CA 945581588657308
Common questions
What is Mark Stephen Singer, M.D.'s NPI number?
Mark Stephen Singer, M.D.'s National Provider Identifier (NPI) is 1962486332, issued on Nov 30, 2005. An NPI identifies a provider in billing; it is not a license.
Where is Mark Stephen Singer, M.D. located?
The NPPES record lists a practice address at 3334 Sterling CT, Napa, CA, 94558. Phone: (707) 365-5151. Providers update this record themselves, so call before visiting.
How can I verify Mark Stephen Singer, M.D.'s license?
NPPES lists California license number G53924, 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 Stephen Singer, M.D. prescribe under Medicare Part D?
In 2024, Mark Stephen Singer, M.D. had 3,444 Medicare Part D claims for 160 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.