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Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Mrs. Marissa Louise Sitz, RN

School Registered Nurse in Ontario, CA · enumerated 2025.

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

National Provider Identifier

1538974100

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Registry record

Entity type Individual (Type 1)
Name Mrs. Marissa Louise Sitz
Credential RN
Sex Female
Practice address 950 W D St, Ontario, CA, 91762
Phone (909) 418-6428
Enumeration date Feb 11, 2025
Last updated in NPPES Feb 11, 2025

Taxonomy & licenses

163WS0200X School Registered Nurse Nursing Service Providers · License 396664 (CA) Primary
RN · Registered Nurse: A nurse who completed an accredited nursing program and passed the NCLEX-RN licensure exam. About the RN 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 Marissa Sitz's NPI record?
Cross-check NPI 1538974100 against the official CMS registry at npiregistry.cms.hhs.gov. This page mirrors the same public NPPES data with a monthly snapshot.
Is NPI 1538974100 active?
Yes, as of the latest NPPES snapshot, NPI 1538974100 is active (record last updated 2025-02-11).

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2025-02-11.