Regan Castellanos, DNP, APRN, CPNP-AC
Regan Castellanos, DNP, APRN, CPNP-AC is a Critical Care Pediatric Nurse Practitioner in Houston, TX, registered under NPI 1427980374.
Getting there
The practice address on file is 6411 FANNIN ST, Houston, TX 77030. 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 |
|---|---|---|
| 1241673 | TX | Critical Care Pediatric Nurse Practitioner primary |
This provider holds licence 1241673 issued in TX. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
What Pediatrics, Critical Care covers
Definition to come... NUCC Health Care Provider Taxonomy, code 363LP0222X
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 | 1427980374 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jun 2, 2026 |
| Last updated | Jul 22, 2026 |
| Status | Active |
| Sole proprietor | No |
| Gender | Female |
| Credential | DNP, APRN, CPNP-AC |
| Practice address |
6411 FANNIN ST Houston, TX 77030 (713) 704-5437 |
| Mailing address |
6410 FANNIN ST STE 420 Houston, TX 77030 |
| Other names |
Regan Williams Former Legal Business Name |
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 | 4 | 2 | 7 | 9 | 8 | 0 | 3 | 7 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 4 | 4 | 7 | 9 | 8 | 0 | 3 | 5 |
Sum = 66 · next multiple of 10 = 70 · check digit = 4 · actual last digit = 4
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.