Mary Johnston, MD
Mary Johnston, MD is a Geriatric Psychiatry Physician in Baltimore, MD, registered under NPI 1881670958.
Getting there
The practice address on file is 600 N WOLFE STREET JOHNS HOPKINS UNIVERSITY SCHOOL OF MEDICINE, Baltimore, MD 21287. 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 |
|---|---|---|
| 9500105 | NC | Geriatric Psychiatry Physician primary |
This provider holds licence 9500105 issued in NC. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
- Status
- Approved
- Provider type
- Practitioner - Psychiatry
- PAC ID
- 6507872330
- Enrollment ID
- I20060302000323
Medicare enrolment is recorded as approved under the provider type Practitioner - Psychiatry. 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.
What Geriatric Psychiatry covers
Geriatric Psychiatry is a subspecialty with psychiatric expertise in prevention, evaluation, diagnosis and treatment of mental and emotional disorders in the elderly, and improvement of psychiatric care for healthy and ill elderly patients. NUCC Health Care Provider Taxonomy, code 2084P0805X
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 | 1881670958 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Dec 20, 2005 |
| Last updated | Sep 18, 2012 |
| Status | Active |
| Sole proprietor | No |
| Gender | Female |
| Credential | MD |
| Practice address |
600 N WOLFE STREET JOHNS HOPKINS UNIVERSITY SCHOOL OF MEDICINE Baltimore, MD 21287 (410) 955-5147 |
| Mailing address |
9910 FRANKLIN SQUARE DRIVE SUITE 2110 JOHNS HOPKINS UNIVERSITY REIMBURSEMENT COORDINATOR White Marsh, MD 21236 |
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 | 8 | 1 | 6 | 7 | 0 | 9 | 5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 8 | 7 | 1 | 3 | 7 | 0 | 9 | 1 |
Sum = 62 · next multiple of 10 = 70 · 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.