Douglas Zhang, M.D.
Douglas Zhang, M.D. is a Geriatric Medicine (Family Medicine) Physician in San Leandro, CA, registered under NPI 1023074341. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
The practice address on file is 13851 E 14TH ST, San Leandro, CA 94578. 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 |
|---|---|---|
| A63200 | CA | Geriatric Medicine (Family Medicine)… primary |
This provider holds licence A63200 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 - General Practice
- PAC ID
- 4183626625
Medicare enrolment is recorded as approved under the provider type Practitioner - General Practice. This means the provider is enrolled to bill Medicare, though it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
What Geriatric Medicine covers
A family medicine physician with special knowledge of the aging process and special skills in the diagnostic, therapeutic, preventive and rehabilitative aspects of illness in the elderly. This specialist cares for geriatric patients in the patient's home, the office, long-term care settings such as nursing homes, and the hospital. NUCC Health Care Provider Taxonomy, code 207QG0300X
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 | 1023074341 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Apr 25, 2006 |
| Last updated | Mar 23, 2011 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | M.D. |
| Practice address |
13851 E 14TH ST San Leandro, CA 94578 (510) 351-2100 Fax (510) 357-3389 |
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 | 0 | 2 | 3 | 0 | 7 | 4 | 3 | 4 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 0 | 4 | 3 | 0 | 7 | 8 | 3 | 8 |
Sum = 59 · next multiple of 10 = 60 · check digit = 1 · actual last digit = 1
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.