Margaret Wallhagen, RN, GNP, PHD
Margaret Wallhagen, RN, GNP, PHD is a Gerontology Nurse Practitioner in San Francisco, CA, registered under NPI 1245331222.
Getting there
The practice address on file is 2 KORET WAY N631, San Francisco, CA 94143. 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 |
|---|---|---|
| 181577 | CA | Gerontology Nurse Practitioner primary |
This provider holds licence 181577 issued in CA. 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 Gerontology covers
Definition to come... NUCC Health Care Provider Taxonomy, code 363LG0600X
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 | 1245331222 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Sep 25, 2006 |
| Last updated | Jul 8, 2007 |
| Status | Active |
| Sole proprietor | No |
| Credential | RN, GNP, PHD |
| Practice address |
2 KORET WAY N631 San Francisco, CA 94143 (415) 476-4965 Fax (415) 476-8899 |
| Mailing address |
8 PARK TER Mill Valley, CA 94941 |
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 | 2 | 4 | 5 | 3 | 3 | 1 | 2 | 2 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 2 | 8 | 5 | 6 | 3 | 2 | 2 | 4 |
Sum = 58 · next multiple of 10 = 60 · check digit = 2 · actual last digit = 2
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.