Grace Hennessy, M.D.
Grace Hennessy, M.D. is an Addiction Psychiatry Physician in New York, NY, registered under NPI 1518910975.
Getting there
The practice address on file is 423 E 23RD ST 11M, New York, NY 10010. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| 229548 | NY | Addiction Psychiatry Physician primary |
This provider holds licence 229548 issued in NY. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
What Addiction Psychiatry covers
Addiction Psychiatry is a subspecialty of psychiatry that focuses on evaluation and treatment of individuals with alcohol, drug, or other substance-related disorders, and of individuals with dual diagnosis of substance-related and other psychiatric disorders. NUCC Health Care Provider Taxonomy, code 2084P0802X
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1518910975 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | May 18, 2006 |
| Last updated | Jul 8, 2007 |
| Status | Active |
| Sole proprietor | No |
| Gender | Female |
| Credential | M.D. |
| Practice address |
423 E 23RD ST 11M New York, NY 10010 (212) 686-7500 |
| Mailing address |
321 W 54TH ST APARTMENT 614 New York, NY 10019 |
| Other names |
Grace O'leary Former Legal Business Name |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 5 | 1 | 8 | 9 | 1 | 0 | 9 | 7 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 5 | 2 | 8 | 9 | 1 | 0 | 9 | 5 |
Sum = 65 · next multiple of 10 = 70 · check digit = 5 · actual last digit = 5
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.