Mary Michael Westerholm, M.D.
Internal Medicine Physician · Winfield, IL
Mary Michael Westerholm, M.D. is an internal medicine physician with a practice address in Winfield, Illinois, and NPI 1790951093, issued on May 6, 2008. Check the license (Illinois 036116854, as entered in NPPES) on the Illinois Department of Financial and Professional Regulation; the Medicare figures below come from public CMS files.
- Name
- Mary Michael Westerholm
- Credential
- M.D.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- 036116854 IL
Self-reported in NPPES; status is on the state search - Practice location
- 25 N Winfield RD, Winfield, IL 60190
- Phone
- (630) 653-0848
- Enumerated
- May 6, 2008
- Record last updated
- Apr 15, 2013 (not updated in 13 years: call before relying on the address or phone)
- Fax
- (630) 653-7746
- Medicaid ID
- 036116854 IL
- Medicare enrollment
- Enrolled (PECOS I20081023000375); accepts Medicare assignment
- Medical or professional school
- Loyola University Of Chicago, Stritch School Of Medicine, 2004
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 7,238 in Illinois → Look up another NPI →
Also registered at 25 N Winfield RD
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Mary Michael Westerholm in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersIllinois Department of Financial and Professional Regulation
Search for license 036116854Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
87% fewer Medicare Part D claims than the average internal medicine physician in 2024
410 Medicare Part D claims for 28 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D.
Most prescribed
- Atorvastatin Calcium28 claims
- Gabapentin20 claims
- Ozempic20 claims
- Amlodipine Besylate18 claims
- Metformin Hcl15 claims
- Levothyroxine Sodium12 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.
Bills Medicare through 2 group practices
- Central Dupage Physician GroupLisle, IL
- Lawndale Christian Health CenterChicago, IL
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Mary Michael Westerholm among 7,238 internal medicine physician records in Illinois
Mary Michael Westerholm, M.D. is one of 7,238 internal medicine physician records with a practice address in Illinois. 73% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2008, is newer than 45% of them.
- NPI issued2008 · 45% of these records are older, 51% newer
- In a Medicare fileYes · 73% of these records are
- In the CMS Doctors and Clinicians fileYes · 50% of these records are
- Graduated2004 · median 2003 among the 3,580 with a school on file
- Record last updated2013 · 47% 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 Illinois practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
19 internal medicine physician records list a practice address in Winfield
They are 19 of the 778 NPPES records with a practice address in Winfield, and 7,238 internal medicine physician records in Illinois.
All 7,238 in Illinois → Every provider in Winfield → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Radha Chirumamilla, M.D.Winfield, IL 601901649560129
- Marc Conte-Russian, D.O.Winfield, IL 601901427378413
- Susan Felber, M.D.Winfield, IL 601901326096637
- Alexandra Frogameni, M.D.Winfield, IL 601901669736583
- Lisa Groskopf, DOWinfield, IL 601901295753689
- Sana Jafri, MDWinfield, IL 601901467793463
- Michelle Jao, MDWinfield, IL 601901083632947
- Jose Magana, MDWinfield, IL 601901447261847
Common questions
What is Mary Michael Westerholm, M.D.'s NPI number?
Mary Michael Westerholm, M.D.'s National Provider Identifier (NPI) is 1790951093, issued on May 6, 2008. An NPI identifies a provider in billing; it is not a license.
Where is Mary Michael Westerholm, M.D. located?
The NPPES record lists a practice address at 25 N Winfield RD, Winfield, IL, 60190. Phone: (630) 653-0848. Providers update this record themselves, so call before visiting.
How can I verify Mary Michael Westerholm, M.D.'s license?
NPPES lists Illinois license number 036116854, as entered by the provider. Search the Illinois Department of Financial and Professional Regulation at https://idfpr.illinois.gov/checklicense.html. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Mary Michael Westerholm, M.D. prescribe under Medicare Part D?
In 2024, Mary Michael Westerholm, M.D. had 410 Medicare Part D claims for 28 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.