Michael Mayer
Internal Medicine Physician · Chicago, IL
Michael Mayer is an internal medicine physician with a practice address in Chicago, Illinois, and NPI 1871175760, issued on Apr 21, 2021. Check the license (Illinois 125.077486, as entered in NPPES) on the Illinois Department of Financial and Professional Regulation; the Medicare figures below come from public CMS files.
- Name
- Michael Mayer
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- 125.077486 IL
Self-reported in NPPES; status is on the state search - Practice location
- 5841 S. Maryland Ave., Chicago, IL 60637
- Phone
- (773) 702-6840
- Enumerated
- Apr 21, 2021
- Record last updated
- Jun 23, 2021 (not updated in 5 years: call before relying on the address or phone)
- Fax
- (773) 834-3950
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 7,238 in Illinois → Look up another NPI →
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A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Michael Mayer 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 125.077486Check 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 62 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. 22 claims were for opioids.
Most prescribed
- Atorvastatin Calcium40 claims
- Gabapentin27 claims
- Amlodipine Besylate18 claims
- Metformin Hcl15 claims
- Xtampza Er15 claims
- Spironolactone14 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.
Michael Mayer among 7,238 internal medicine physician records in Illinois
Michael Mayer 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 2021, is newer than 74% of them.
- NPI issued2021 · 74% of these records are older, 22% newer
- In a Medicare fileYes · 73% of these records are
- In the CMS Doctors and Clinicians fileNo · 50% of these records are
- Record last updated2021 · 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).
2,867 internal medicine physician records list a practice address in Chicago
They are 2,867 of the 63,379 NPPES records with a practice address in Chicago, and 7,238 internal medicine physician records in Illinois.
All 7,238 in Illinois → Every provider in Chicago → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
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- Kristine Bordenave, M.D.Chicago, IL 606371811009368
- Andrew DavisChicago, IL 606371275642167
- Hatim HassanChicago, IL 606371417970385
- Keiki Hinami, M.D.Chicago, IL 606371437136785
- David Liebovitz, MDChicago, IL 606371972564748
- Thomas Mason, M.D.Chicago, IL 606371730114505
Common questions
What is Michael Mayer's NPI number?
Michael Mayer's National Provider Identifier (NPI) is 1871175760, issued on Apr 21, 2021. An NPI identifies a provider in billing; it is not a license.
Where is Michael Mayer located?
The NPPES record lists a practice address at 5841 S. Maryland Ave., Chicago, IL, 60637. Phone: (773) 702-6840. Providers update this record themselves, so call before visiting.
How can I verify Michael Mayer's license?
NPPES lists Illinois license number 125.077486, 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 Michael Mayer prescribe under Medicare Part D?
In 2024, Michael Mayer had 410 Medicare Part D claims for 62 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.