John Frost, MDPHD
John Frost, MDPHD is a Diagnostic Radiology Physician in New Haven, CT, registered under NPI 1831171552. 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 800 HOWARD AVE, New Haven, CT 06519. 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 |
|---|---|---|
| 042865 | CT | Diagnostic Radiology Physician primary |
| 042865 | CT | Nuclear Medicine Physician |
This provider holds licence 042865 issued in CT. 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 Diagnostic Radiology covers
A radiologist who utilizes x-ray, radionuclides, ultrasound and electromagnetic radiation to diagnose and treat disease. NUCC Health Care Provider Taxonomy, code 2085R0202X
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 | |
|---|---|---|---|---|
| 2085R0202X | Diagnostic Radiology Physician Diagnostic Radiology | 042865 | CT | primary |
| 207U00000X | Nuclear Medicine Physician | 042865 | CT |
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 | 1831171552 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Nov 17, 2005 |
| Last updated | Sep 11, 2025 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | MDPHD |
| Practice address |
800 HOWARD AVE New Haven, CT 06519 (203) 785-2140 Fax (203) 785-6414 |
| Mailing address |
300 GEORGE ST 6TH FLOOR PO BOX 9805 New Haven, CT 06536 |
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 | 8 | 3 | 1 | 1 | 7 | 1 | 5 | 5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 8 | 6 | 1 | 2 | 7 | 2 | 5 | 1 |
Sum = 58 · next multiple of 10 = 60 · 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.