Provider Profile
Marianna Z. Grennan, LCSW R
Unclaimed ProfileAbout Marianna Grennan
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Specialty
Credentials & Licensing
License numbers are what the provider reported to NPPES when the NPI was issued or updated. NPPES does not verify licensure; confirm current standing with the state licensing board.
Medicare information
Exactly as CMS reports it (National Downloadable File, Opt-Out Affidavits, Order & Referring). Not an insurance directory; confirm coverage with the office.
Contact Information
- (631) 271-5617
- Email not available
Practice Locations
900 WALT WHITMAN ROAD SUITE 300
Melville, NY 11747
Related providers
Connections drawn from the registry and from what providers have told us. A link here is not a referral or an endorsement.
Other clinical social workers at this location 8
Same specialty, same street address — most likely the same department or group.
Related specialists at this location 6
Clinically related specialties at the same address — the people this provider most likely works alongside.
Also at this address 4
Providers at the same street address. Each files their own registry entry, so a shared practice often appears under several different names.
More connections — 7 related providers in 1 group
Common questions
What does Marianna Z. Grennan specialize in?
Marianna Z. Grennan is a clinical social worker in Melville, NY. That is the designation recorded for this NPI in the federal registry.
NPI registry
Where is Marianna Z. Grennan located?
Marianna Z. Grennan is listed at 900 Walt Whitman Road Suite 300, Melville, NY 11747. Addresses come from the NPI registry and can lag a move, so confirm before travelling.
NPI registry
What is Marianna Z. Grennan's phone number?
The number on file is (631) 271-5617. Guide.md cannot book appointments or pass on messages — please call the office directly.
NPI registry
What is Marianna Z. Grennan's NPI number?
Marianna Z. Grennan's National Provider Identifier is 1013188390. It is issued by the Centers for Medicare & Medicaid Services and is unique and permanent — it does not change if they move practice.
NPI registry
How long has Marianna Z. Grennan been practicing?
Marianna Z. Grennan has 18+ years experience. Registered with an NPI since 2008. National Provider Identifiers only began in 2005, so a provider who qualified earlier may have practiced for longer than this.
NPI registry
Has Marianna Z. Grennan confirmed this information?
Not yet. This profile is built from public federal data and has not been confirmed by Marianna Z. Grennan. If this is you, claiming it is free.
Guide.md
Provider data sourced from the NPPES NPI Registry and CMS public datasets. Information is provided for reference and is not medical advice.