Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. Michael Harry Mastromichalis, M.D.

Urology Physician in Fenton, MO · enumerated 2007.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1346444700

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Registry record

Entity type Individual (Type 1)

Name Dr. Michael Harry Mastromichalis

Credential M.D.

Sex Male

Practice address 1011 Bowles Ave Ste 425, Fenton, MO, 63026

Phone (636) 496-5030

Fax (636) 496-5025

Enumeration date Jun 12, 2007

Last updated in NPPES Nov 5, 2020

Taxonomy & licenses

208800000X Urology Physician Allopathic & Osteopathic Physicians · License 2008016598 (MO) Primary

MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

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Frequently asked questions

How do I verify Michael Mastromichalis's NPI record?

Cross-check NPI 1346444700 against the official CMS registry at npiregistry.cms.hhs.gov. This page mirrors the same public NPPES data with a monthly snapshot.

Is NPI 1346444700 active?

Yes, as of the latest NPPES snapshot, NPI 1346444700 is active (record last updated 2020-11-05).

Other providers at this practice address

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Joel Hammond Surgery Physician · Fenton, MO NPI 1790892552 Laura Grimmer Surgery Physician · Fenton, MO NPI 1124314497 Courtney Cockerell Gastroenterology Physician · Fenton, MO NPI 1346504644 Patricia Hodgins Urology Physician · Fenton, MO NPI 1457791808 Janani Vigneswaran Thoracic Surgery (Cardiothoracic Vascular Surgery) Physician · Fenton, MO NPI 1447609821 Jeannette Bender Family Nurse Practitioner · Fenton, MO NPI 1104478494 Jeffrey Orf Urology Physician · Fenton, MO NPI 1417578527 Lindsey Adams Nurse Practitioner · Fenton, MO NPI 1326611757

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2020-11-05.