John Marcum, MD
John Marcum, MD is an Allergy & Immunology Physician in St Clair, MO, registered under NPI 1720113053.
Getting there
The practice address on file is 1020 ST CLAIR PLAZA, St Clair, MO 63077. 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 |
|---|---|---|
| R3G15 | MO | Allergy & Immunology Physician primary |
| G38741 | CA | Allergy & Immunology Physician |
Licences are recorded in 2 states: MO, CA. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
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.
Licensed in 2 states
This provider holds licences in 2 states: California and Missouri. The practice address on file is in St Clair, MO, 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
- R3G15
- Specialty
- Allergy & Immunology 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 Allergy & Immunology covers
An allergist-immunologist is trained in evaluation, physical and laboratory diagnosis, and management of disorders involving the immune system. Selected examples of such conditions include asthma, anaphylaxis, rhinitis, eczema, and adverse reactions to drugs, foods, and insect stings as well as immune deficiency diseases (both acquired and congenital), defects in host defense, and problems related to autoimmune disease, organ transplantation, or malignancies of the immune system. NUCC Health Care Provider Taxonomy, code 207K00000X
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 | |
|---|---|---|---|---|
| 207K00000X | Allergy & Immunology Physician | R3G15 | MO | primary |
| 207K00000X | Allergy & Immunology Physician | G38741 | CA |
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 | 1720113053 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Feb 23, 2007 |
| Last updated | Jun 26, 2014 |
| Status | Active |
| Sole proprietor | No |
| Credential | MD |
| Practice address |
1020 ST CLAIR PLAZA St Clair, MO 63077 (636) 629-6030 Fax (636) 629-6030 |
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 | 2 | 0 | 1 | 1 | 3 | 0 | 5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 7 | 4 | 0 | 2 | 1 | 6 | 0 | 1 |
Sum = 47 · next multiple of 10 = 50 · check digit = 3 · actual last digit = 3
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.