Douglas Tollefsen, MD
Douglas Tollefsen, MD is a Hematology (Internal Medicine) Physician in Saint Louis, MO, registered under NPI 1679599815.
Getting there
The practice address on file is 4921 PARKVIEW PL FL 7 7TH FL, Saint Louis, MO 63110. 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 |
|---|---|---|
| R9558 | MO | Hematology (Internal Medicine) Physician primary |
This provider holds licence R9558 issued in MO. 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 Hematology covers
An internist with additional training who specializes in diseases of the blood, spleen and lymph. This specialist treats conditions such as anemia, clotting disorders, sickle cell disease, hemophilia, leukemia and lymphoma. NUCC Health Care Provider Taxonomy, code 207RH0000X
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 | 1679599815 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jul 14, 2006 |
| Last updated | Jan 29, 2018 |
| Status | Active |
| Sole proprietor | No |
| Credential | MD |
| Practice address |
4921 PARKVIEW PL FL 7 7TH FL Saint Louis, MO 63110 (314) 362-8808 Fax (314) 362-8826 |
| Mailing address |
660 S EUCLID AVE C B 8125 Saint Louis, MO 63110 |
| Other identifiers |
201385101
· Medicaid (MO) ENROLLED · Medicaid (IL) |
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 | 6 | 7 | 9 | 5 | 9 | 9 | 8 | 1 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 6 | 5 | 9 | 1 | 9 | 9 | 8 | 2 |
Sum = 75 · next multiple of 10 = 80 · check digit = 5 · actual last digit = 5
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.