Are NPI numbers public?

Yes. NPI numbers are public federal identifiers in CMS NPPES. This page shows the public NPPES facts Fonteum has for NPI 1538165782: provider name, entity type, taxonomy, practice location, enumeration date, last-updated date, and source snapshot date. It does not include patient information.

What does the NPI record show for Mark Castellanet?

Mark Castellanet (NPI 1538165782) appears in CMS NPPES as cardiologist in Los Alamitos, CA. NPPES is administrative identity data submitted to CMS by providers and organizations; this page displays the source snapshot date as 2026-05-06.

Does this page assign a provider score?

No derived score is assigned on this provider page. NPPES is an identity registry; when a CMS QPP MIPS value is available, Fonteum displays that public CMS value with its source, and absence of a MIPS value is not a quality signal.

Does no exclusion match amount to a clearance?

Coverage is indeterminate, so this page makes no negative exclusion determination. This is not a clearance; check the current issuing-agency lists.

Where does the provider data come from?

The identity fields come from CMS NPPES. Additional sections appear only when a public source has a matching row, such as CMS PECOS, CMS Open Payments, Medicare Part D, CMS QPP MIPS, OIG LEIE, or state Medicaid exclusion lists. Source and date metadata appears where the response supplies it; unavailable dates are labeled.

Mark Castellanet — NPI 1538165782: exclusion

Name: Provider record — NPI 1538165782 (Mark Castellanet)
Creator: Fonteum
License: https://www.usa.gov/government-works

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Mark Castellanet — NPI 1538165782: exclusion — Fonteum

Cross-source identity

Sources that publish this NPI

National Provider Identifier 1538165782 appears in the source rows shown below. Sources that do not publish NPI use their own identifiers and are not treated as deterministic NPI matches. Chips show response-supplied dates when available; otherwise they are labeled date unavailable.

NPPES

Federal sources carrying NPI 1538165782
Federal source	Key	What it provides	Source & date
CMS NPPES	NPI 1538165782	Registry identity — cardiologist, taxonomy 207RC0000X	Source:CMS NPPESSnapshot 2026-05-06

Mark Castellanet

Public NPPES answers

Are NPI numbers public?

What does the NPI record show for Mark Castellanet?

Does this page assign a provider score?

Does no exclusion match amount to a clearance?

Where does the provider data come from?

Sources that publish this NPI

MIPS quality score

Standing

Who owns, operates, or is affiliated with this provider

Retained versions for this record

Mark Castellanet

Public NPPES answers

Are NPI numbers public?

What does the NPI record show for Mark Castellanet?

Data-use and correction resources.

Does this page assign a provider score?

Does no exclusion match amount to a clearance?

Where does the provider data come from?

Sources that publish this NPI

MIPS quality score

Standing

Who owns, operates, or is affiliated with this provider

Retained versions for this record

Context for this record