Mark Casillas, M.D.
Mark Casillas, M.D. is a Surgery Physician in Knoxville, TN, registered under NPI 1245458082. 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 1934 ALCOA HIGHWAY BLDG D, SUITE 370, Knoxville, TN 37920. 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 |
|---|---|---|
| LP00968 | RI | Surgery Physician primary |
| 48676 | TN | Colon & Rectal Surgery Physician |
Licences are recorded in 2 states: RI, TN. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
- Status
- Approved
- Provider type
- Practitioner - Colorectal Surgery (proctology)
- PAC ID
- 7012165988
Medicare enrolment is recorded as approved under the provider type Practitioner - Colorectal Surgery (proctology). 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.
Licensed in 2 states
This provider holds licences in 2 states: Rhode Island and Tennessee. The practice address on file is in Knoxville, TN, but a licence in another state usually means they see patients there too — either at a second location or by telehealth. If the address above is far from you, it is worth calling to ask whether they practise closer to where you live.
- Licence
- 48676
- Specialty
- Colon & Rectal Surgery Physician
Licence numbers are self-reported to NPPES at registration. They do not confirm a licence is currently active, in good standing, or valid for the specialty shown — only the state board can tell you that, which is why we link to each one.
What Surgery covers
A general surgeon has expertise related to the diagnosis - preoperative, operative and postoperative management - and management of complications of surgical conditions in the following areas: alimentary tract; abdomen; breast, skin and soft tissue; endocrine system; head and neck surgery; pediatric surgery; surgical critical care; surgical oncology; trauma and burns; and vascular surgery. General surgeons increasingly provide care through the use of minimally invasive and endoscopic techniques. Many general surgeons also possess expertise in transplantation surgery, plastic surgery and cardiothoracic surgery. NUCC Health Care Provider Taxonomy, code 208600000X
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 | |
|---|---|---|---|---|
| 208600000X | Surgery Physician | LP00968 | RI | primary |
| 208C00000X | Colon & Rectal Surgery Physician | 48676 | TN |
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 | 1245458082 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Apr 24, 2007 |
| Last updated | Feb 4, 2014 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | M.D. |
| Practice address |
1934 ALCOA HIGHWAY BLDG D, SUITE 370 Knoxville, TN 37920 (865) 305-5335 Fax (865) 305-8840 |
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 | 4 | 5 | 8 | 0 | 8 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 2 | 8 | 5 | 8 | 5 | 7 | 0 | 7 |
Sum = 68 · next multiple of 10 = 70 · 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.