Alexander Clerk, M.D.
Alexander Clerk, M.D. is a Sleep Specialist (PhD) in San Jose, CA, registered under NPI 1902911381. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty. 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 455 OCONNOR DR STE 110, San Jose, CA 95128. 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 |
|---|---|---|
| 448 | CA | Sleep Specialist (PhD) primary |
| A36573 | CA | Psychiatry Physician |
This provider holds licence 448 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 - Psychiatry
- PAC ID
- 7911167515
- Enrollment ID
- I20120319000602
Medicare enrolment is recorded as approved under the provider type Practitioner - Psychiatry. 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 Sleep Specialist, PhD covers
Sleep medicine is a clinical specialty with a focus on clinical problems that require accurate diagnosis and treatment. The knowledge base of sleep medicine is derived from many disciplines including neuroanatomy, neurophysiology, respiratory physiology, pharmacology, psychology, psychiatry, neurology, general internal medicine, pulmonary medicine, and pediatrics as well as others. NUCC Health Care Provider Taxonomy, code 173F00000X
All registered taxonomy codes
This provider registers 2 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 173F00000X | Sleep Specialist (PhD) | 448 | CA | primary |
| 2084P0800X | Psychiatry Physician Psychiatry | A36573 | CA |
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 | 1902911381 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Aug 19, 2006 |
| Last updated | Jan 19, 2021 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | M.D. |
| Practice address |
455 OCONNOR DR STE 110 San Jose, CA 95128 (408) 295-4532 Fax (408) 295-4738 |
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 | 9 | 0 | 2 | 9 | 1 | 1 | 3 | 8 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 9 | 0 | 2 | 9 | 1 | 2 | 3 | 7 |
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.