Mark A. Isaeff, M.D.
Internal Medicine Physician · San Antonio, TX
Mark A. Isaeff, M.D. is an internal medicine physician with a practice address in San Antonio, Texas, and NPI 1104815075, issued on Oct 13, 2005. Check the license (Texas K8638, as entered in NPPES) on the Texas Medical Board; the Medicare figures below come from public CMS files.
- Name
- Mark A. Isaeff
- Credential
- M.D.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- K8638 TX
Self-reported in NPPES; status is on the state search - Practice location
- 1303 Mccullough Ave, San Antonio, TX 78212
- Phone
- (210) 572-4431
- Enumerated
- Oct 13, 2005
- Record last updated
- Apr 21, 2011 (not updated in 15 years: call before relying on the address or phone)
- Fax
- (210) 572-4435
- Medicaid IDs
- 144897204 TX
144867202 TX - Medicare enrollment
- Enrolled (PECOS I20100416000231); accepts Medicare assignment
- Medical or professional school
- Georgetown University School Of Medicine, 1998
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 9,175 in Texas → Look up another NPI →
Also registered at 1303 Mccullough Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
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- Neera Bhatia, MDObstetrics & Gynecology Physician1760428619
Verify Mark A. Isaeff in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersTexas Medical Board
Search for license K8638Check 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% fewer Medicare Part D claims than the average internal medicine physician in 2024
2,918 Medicare Part D claims for 181 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. 11 claims were for opioids.
Most prescribed
- Rosuvastatin Calcium292 claims
- Losartan Potassium209 claims
- Carvedilol186 claims
- Levothyroxine Sodium173 claims
- Doxycycline Hyclate105 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 A. Isaeff among 9,175 internal medicine physician records in Texas
Mark A. Isaeff, M.D. is one of 9,175 internal medicine physician records with a practice address in Texas. 82% 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, 91% newer
- In a Medicare fileYes · 82% of these records are
- In the CMS Doctors and Clinicians fileYes · 66% of these records are
- Graduated1998 · median 2004 among the 6,088 with a school on file
- Record last updated2011 · 49% 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 Texas practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
657 internal medicine physician records list a practice address in San Antonio
They are 657 of the 37,749 NPPES records with a practice address in San Antonio, and 9,175 internal medicine physician records in Texas.
All 9,175 in Texas → Every provider in San Antonio → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- John Anes, M DSan Antonio, TX 782121811981350
- Robert Borrego, MDSan Antonio, TX 782121700872439
- Alexis Miles, MDSan Antonio, TX 782121881663557
- Jaime Moreno, MDSan Antonio, TX 782121144281478
- Aris Nikas, M.D.San Antonio, TX 782121093781890
- Joel Pena, MDSan Antonio, TX 782121588653455
- Enrique Perez-Rodriguez, MDSan Antonio, TX 782121174571434
- Richard Reyna, M.D.San Antonio, TX 782121326014069
Common questions
What is Mark A. Isaeff, M.D.'s NPI number?
Mark A. Isaeff, M.D.'s National Provider Identifier (NPI) is 1104815075, issued on Oct 13, 2005. An NPI identifies a provider in billing; it is not a license.
Where is Mark A. Isaeff, M.D. located?
The NPPES record lists a practice address at 1303 Mccullough Ave, San Antonio, TX, 78212. Phone: (210) 572-4431. Providers update this record themselves, so call before visiting.
How can I verify Mark A. Isaeff, M.D.'s license?
NPPES lists Texas license number K8638, as entered by the provider. Search the Texas Medical Board at https://profile.tmb.state.tx.us/Search.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Mark A. Isaeff, M.D. prescribe under Medicare Part D?
In 2024, Mark A. Isaeff, M.D. had 2,918 Medicare Part D claims for 181 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.