Mark Xu, MD
Mark Xu, MD is an Orthopaedic Surgery Physician in San Francisco, CA, registered under NPI 1003699471. This provider registers 3 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 2540 23RD ST BLDG 7, 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 |
|---|---|---|
| A188903 | CA | Orthopaedic Surgery Physician primary |
| A188903 | CA | Orthopaedic Surgery of the Spine Physician |
| A188903 | CA | Orthopaedic Trauma Physician |
This provider holds licence A188903 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 - Orthopedic Surgery
- PAC ID
- 8022462514
Medicare enrolment is recorded as approved under the provider type Practitioner - Orthopedic Surgery. 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 Orthopaedic Surgery covers
An orthopaedic surgeon is trained in the preservation, investigation and restoration of the form and function of the extremities, spine and associated structures by medical, surgical and physical means. An orthopaedic surgeon is involved with the care of patients whose musculoskeletal problems include congenital deformities, trauma, infections, tumors, metabolic disturbances of the musculoskeletal system, deformities, injuries and degenerative diseases of the spine, hands, feet, knee, hip, shoulder and elbow in children and adults. An orthopaedic surgeon is also concerned with primary and secondary muscular problems and the effects of central or peripheral nervous system lesions of the musculoskeletal system. NUCC Health Care Provider Taxonomy, code 207X00000X
All registered taxonomy codes
This provider registers 3 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 207X00000X | Orthopaedic Surgery Physician | A188903 | CA | primary |
| 207XS0117X | Orthopaedic Surgery of the Spine Physician Orthopaedic Surgery of the Spine | A188903 | CA | |
| 207XX0801X | Orthopaedic Trauma Physician Orthopaedic Trauma | A188903 | 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 | 1003699471 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Aug 17, 2023 |
| Last updated | Aug 17, 2023 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | MD |
| Practice address |
2540 23RD ST BLDG 7 San Francisco, CA 94143 (415) 476-2124 |
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 | 0 | 3 | 6 | 9 | 9 | 4 | 7 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 0 | 0 | 3 | 3 | 9 | 9 | 4 | 5 |
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.