Karen Theo Isselbacher, MD
Internal Medicine Physician · Wellesley, MA
Karen Theo Isselbacher, MD is an internal medicine physician with a practice address in Wellesley, Massachusetts, and NPI 1508822867, issued on Apr 25, 2006. Check the license (Massachusetts 59434, as entered in NPPES) on the Massachusetts Board of Registration in Medicine; the Medicare figures below come from public CMS files.
- Name
- Karen Theo Isselbacher
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- 59434 MA
Self-reported in NPPES; status is on the state search - Practice location
- 70 Hastings St, Wellesley, MA 02481
- Phone
- (781) 444-3550
- Enumerated
- Apr 25, 2006
- Record last updated
- Jan 23, 2024
- Fax
- (781) 444-3551
- Medicare enrollment
- Enrolled (PECOS I20060315000417); accepts Medicare assignment
- Medical or professional school
- Boston University School Of Medicine, 1985
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 6,825 in Massachusetts → Look up another NPI →
Also registered at 70 Hastings St
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Christine Harrington, M.D.Internal Medicine Physician1306951363
- Li Tso, M.D.Internal Medicine Physician1467443150
Verify Karen Theo Isselbacher in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMassachusetts Board of Registration in Medicine
Search for license 59434Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
73% fewer Medicare Part D claims than the average internal medicine physician in 2024
844 Medicare Part D claims for 80 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D.
Most prescribed
- Levothyroxine Sodium54 claims
- Atorvastatin Calcium39 claims
- Rosuvastatin Calcium39 claims
- Omeprazole34 claims
- Amlodipine Besylate28 claims
- Losartan Potassium28 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: $46.02
2 payments; by number, the most common kind was food and beverage; the largest payer was Pfizer Inc. The 50,334 providers of this specialty with any payment received $1,303.06 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.
Bills Medicare through one group practice
- Private Health Care Group, LLCWellesley, MA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Karen Theo Isselbacher among 6,825 internal medicine physician records in Massachusetts
Karen Theo Isselbacher, MD is one of 6,825 internal medicine physician records with a practice address in Massachusetts. 75% 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 12% of them.
- NPI issued2006 · 12% of these records are older, 54% newer
- In a Medicare fileYes · 75% of these records are
- In the CMS Doctors and Clinicians fileYes · 60% of these records are
- Graduated1985 · median 2004 among the 4,103 with a school on file
- Record last updated2024 · 64% 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 Massachusetts practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
81 internal medicine physician records list a practice address in Wellesley
They are 81 of the 1,117 NPPES records with a practice address in Wellesley, and 6,825 internal medicine physician records in Massachusetts.
All 6,825 in Massachusetts → Every provider in Wellesley → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Mitchell Abramson, M.D.Wellesley Hills, MA 024811417952284
- Dea Angiolillo, M.D.Wellesley, MA 024811649241985
- Mary Barker, M.D.Wellesley, MA 024811215908132
- Peter Britton, M.D.Wellesley, MA 024811184695082
- Mary Brogan, M.D.Wellesley, MA 024811912987454
- Carol Burd, M.D.Wellesley, MA 024811114998036
- Nancy Corliss, MDWellesley, MA 024811699763482
- Steven Flier, M.D.Wellesley, MA 024811013905751
Common questions
What is Karen Theo Isselbacher, MD's NPI number?
Karen Theo Isselbacher, MD's National Provider Identifier (NPI) is 1508822867, issued on Apr 25, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Karen Theo Isselbacher, MD located?
The NPPES record lists a practice address at 70 Hastings St, Wellesley, MA, 02481. Phone: (781) 444-3550. Providers update this record themselves, so call before visiting.
How can I verify Karen Theo Isselbacher, MD's license?
NPPES lists Massachusetts license number 59434, as entered by the provider. Search the Massachusetts Board of Registration in Medicine at https://findmydoctor.mass.gov/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Karen Theo Isselbacher, MD prescribe under Medicare Part D?
In 2024, Karen Theo Isselbacher, MD had 844 Medicare Part D claims for 80 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.