Ryan Casarella, M.D.
Ryan Casarella, M.D. is an Emergency Medicine Physician in Greenwich, CT, registered under NPI 1740643998.
Getting there
The practice address on file is 5 PERRYRIDGE RD, Greenwich, CT 06830. 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 |
|---|---|---|
| 314567-01 | NY | Emergency Medicine Physician primary |
| 19025 | NV | Emergency Medicine Physician |
Licences are recorded in 2 states: NY, NV. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
- Status
- Approved
- Provider type
- Practitioner - Emergency Medicine
- PAC ID
- 7517296346
Enrolled in Medicare 2 times, across 2 states:
| State | Enrollment ID | Provider type |
|---|---|---|
| New York | I20220725000830 | Practitioner - Emergency Medicine |
| Connecticut | I20250214001205 | Practitioner - Emergency Medicine |
Medicare enrolment is recorded as approved under the provider type Practitioner - Emergency Medicine. There are 2 separate enrolment records across 2 states (NY, CT). Multiple enrolments usually mean the provider bills Medicare from more than one practice location, or has kept an earlier enrolment after moving. Each record carries its own enrolment ID, listed above. 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.
Licensed in 2 states
This provider holds licences in 2 states: Nevada and New York. Multi-state licensure often means the provider works near a state border, covers more than one office, or delivers care 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 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 Emergency Medicine covers
An emergency physician focuses on the immediate decision making and action necessary to prevent death or any further disability both in the pre-hospital setting by directing emergency medical technicians and in the emergency department. The emergency physician provides immediate recognition, evaluation, care, stabilization and disposition of a generally diversified population of adult and pediatric patients in response to acute illness and injury. NUCC Health Care Provider Taxonomy, code 207P00000X
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 | |
|---|---|---|---|---|
| 207P00000X | Emergency Medicine Physician | 314567-01 | NY | primary |
| 207P00000X | Emergency Medicine Physician | 19025 | NV |
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 | 1740643998 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Apr 4, 2016 |
| Last updated | Feb 11, 2025 |
| Status | Active |
| Sole proprietor | No |
| Credential | M.D. |
| Practice address |
5 PERRYRIDGE RD Greenwich, CT 06830 (203) 863-3000 |
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 | 7 | 4 | 0 | 6 | 4 | 3 | 9 | 9 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 7 | 8 | 0 | 3 | 4 | 6 | 9 | 9 |
Sum = 72 · next multiple of 10 = 80 · check digit = 8 · actual last digit = 8
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.