John Armstrong, MD
John Armstrong, MD is a Gynecology Physician in Napa, CA, registered under NPI 1790875995.
Getting there
The practice address on file is 3434 VILLA LN SUITE 360, Napa, CA 94558. 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 |
|---|---|---|
| 00C378990 | CA | Gynecology Physician primary |
This provider holds licence 00C378990 issued in CA. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
- Status
- Approved
- Provider type
- Practitioner - Obstetrics/gynecology
- PAC ID
- 5698857936
- Enrollment ID
- I20080125000394
Medicare enrolment is recorded as approved under the provider type Practitioner - Obstetrics/gynecology. Being enrolled means the provider can bill Medicare; it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
What Gynecology covers
A physician who specializes in diagnosis, treatment, and management of patients with gynecologic conditions. NUCC Health Care Provider Taxonomy, code 207VG0400X
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 | 1790875995 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Oct 16, 2006 |
| Last updated | Jul 8, 2007 |
| Status | Active |
| Sole proprietor | No |
| Credential | MD |
| Practice address |
3434 VILLA LN SUITE 360 Napa, CA 94558 (707) 257-4317 Fax (707) 257-4319 |
| Other identifiers |
ZZR0009F
· Medicaid (CA) |
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 | 7 | 9 | 0 | 8 | 7 | 5 | 9 | 9 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 7 | 9 | 0 | 7 | 7 | 1 | 9 | 9 |
Sum = 75 · next multiple of 10 = 80 · 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.