NPPES file of Aug 9, 2026

Gary Maassen, M.D.

Internal Medicine Physician · Saint Louis, MO

Gary Maassen, M.D. is an internal medicine physician with a practice address in Saint Louis, Missouri, and NPI 1831170968, issued on Nov 7, 2005. Check the license (Missouri R7H60, as entered in NPPES) on the Missouri Board of Registration for the Healing Arts; the Medicare figures below come from public CMS files.

Record from CMS NPPES, file of Aug 9, 2026 · Medicare files 2024 · method · Verify with CMS →

NPPES recordNPPES file of Aug 9, 2026
1831170968
Name
Gary Maassen
Credential
M.D.
Primary taxonomy
Internal Medicine Physician 207R00000X
License number
R7H60 MO
Self-reported in NPPES; status is on the state search
Practice location
5034 Griffin RD, Saint Louis, MO 63128
Phone
(314) 843-7333
Enumerated
Nov 7, 2005
Record last updated
Sep 24, 2012 (not updated in 14 years: call before relying on the address or phone)
Fax
(314) 843-9946
Entity
Type 1 · individual
Public record from CMS NPPES (open it on the CMS NPI Registry). A record is not a license: verify it with the state board.
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8 nearest internal medicine physician records → All 2,604 in Missouri → Look up another NPI →

Also registered at 5034 Griffin RD

A shared address usually means a shared clinic or building; it does not show who employs whom.

  1. Curt Calcaterra, M.D.Internal Medicine Physician1205827557
  2. Kathleen Cizek, M.D.Internal Medicine Physician1083605331
  3. Marissa Digregorio, DNP, AGNPAdult Health Nurse Practitioner1700561321
  4. James Ebel, M.D.Internal Medicine Physician1174504146
  5. Christopher Espana, M.D.Family Medicine Physician1003922634
  6. Robert Geekie, M.D.Internal Medicine Physician1528059730

Verify Gary Maassen in five checks

  1. 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
  2. 2LicenseActive license and public ordersMissouri Board of Registration for the Healing Arts
    Search for license R7H60    Check the board
  3. 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
  4. 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
  5. 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
Open the Missouri license search

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5% fewer Medicare Part D claims than the average internal medicine physician in 2024

3,009 Medicare Part D claims for 440 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 14% of claims.

  1. Gary Maassen3,009
  2. Specialty average3,176

Most prescribed

  1. Atorvastatin Calcium272 claims
  2. Amlodipine Besylate131 claims
  3. Metoprolol Succinate119 claims
  4. Lisinopril115 claims
  5. Pantoprazole Sodium104 claims
  6. Rosuvastatin Calcium91 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: $16.44

1 payment: food and beverage; the largest payer was Sumitomo Pharma America, 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.

  1. Gary Maassen$16.44
  2. Specialty average$1,303.06

Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.

Gary Maassen among 2,604 internal medicine physician records in Missouri

Gary Maassen, M.D. is one of 2,604 internal medicine physician records with a practice address in Missouri. 77% 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, 92% newer
  • In a Medicare fileYes · 77% of these records are
  • In the CMS Doctors and Clinicians fileNo · 55% of these records are
  • Record last updated2012 · 48% 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 Missouri practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).

941 internal medicine physician records list a practice address in Saint Louis

They are 941 of the 27,605 NPPES records with a practice address in Saint Louis, and 2,604 internal medicine physician records in Missouri.

All 2,604 in Missouri → Every provider in Saint Louis → Internal Medicine Physician nationwide →

The 8 internal medicine physician records with the nearest ZIP codes

  1. Christopher Bowe, MDSaint Louis, MO 631281003816976
  2. Curt Calcaterra, M.D.Saint Louis, MO 631281205827557
  3. Kathleen Cizek, M.D.Saint Louis, MO 631281083605331
  4. Robert Curtin, MDSaint Louis, MO 631281538169495
  5. James Ebel, M.D.Saint Louis, MO 631281174504146
  6. Michael Fedak, M.D.Saint Louis, MO 631281174514384
  7. Patrick Garrett, M.D.Saint Louis, MO 631281669466629
  8. Robert Geekie, M.D.Saint Louis, MO 631281528059730

Common questions

What is Gary Maassen, M.D.'s NPI number?

Gary Maassen, M.D.'s National Provider Identifier (NPI) is 1831170968, issued on Nov 7, 2005. An NPI identifies a provider in billing; it is not a license.

Where is Gary Maassen, M.D. located?

The NPPES record lists a practice address at 5034 Griffin RD, Saint Louis, MO, 63128. Phone: (314) 843-7333. Providers update this record themselves, so call before visiting.

How can I verify Gary Maassen, M.D.'s license?

NPPES lists Missouri license number R7H60, as entered by the provider. Search the Missouri Board of Registration for the Healing Arts at https://www.fsmb.org/contact-a-state-medical-board/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.

How much does Gary Maassen, M.D. prescribe under Medicare Part D?

In 2024, Gary Maassen, M.D. had 3,009 Medicare Part D claims for 440 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.

Written with AI tools from the named public files; every figure is computed from those files (how it is made).

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.