Mary Ann Trephan, MD
NPI 1891752614 · Emergency Medicine Physician · Northridge, CA
Enrolled with Medicare as Practitioner - Emergency Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Mary Ann Trephan, MD is a Emergency Medicine Physician provider in Northridge, CA (NPI 1891752614).
Provider details
- NPI number
- 1891752614
- Entity type
- Individual
- Primary specialty
- Emergency Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Female
- Sole proprietor
- Yes
- License
- G85040 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
20 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)28% of score
568 Medicare services, 2024 (ranked within specialty)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 127 | $136 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 102 | $97 |
| New Patient Office Or Other Outpatient Visit With Low Level of Medical Decision Making, If Using Time, 30 Minutes Or More99203 | 72 | $118 |
| New Patient Office Or Other Outpatient Visit With Moderate Level of Medical Decision Making, If Using Time, 45 Minutes Or More99204 | 66 | $176 |
| X-Ray of Chest, 2 Views71046 | 54 | $38 |
| Manual Urinalysis Test With Examination Using Microscope, Automated81001 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 7 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Cephalexin | 54 | 53 |
| Prednisone | 42 | 40 |
| Azithromycin | 39 | 38 |
| Amoxicillin/Potassium Clavbrand: Amoxicillin-Clavulanate Potass | 32 | 32 |
| Albuterol Sulfatebrand: Albuterol Sulfate Hfa | 31 | 31 |
| Moxifloxacin Hclbrand: Moxifloxacin | 23 | 23 |
| Mupirocin | 15 |
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-04-26
- Last updated
- 2021-12-01
- Certified
- 2021-12-01
Frequently asked questions
- What is Mary Ann Trephan's NPI number?
- Mary Ann Trephan's National Provider Identifier (NPI) is 1891752614, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Mary Ann Trephan's specialty?
- Mary Ann Trephan is listed in the NPPES registry with a primary specialty of Emergency Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Mary Ann Trephan located?
- Mary Ann Trephan's practice location on file with NPPES is 18300 Roscoe Blvd, Northridge, CA 91328.
- What is Mary Ann Trephan's phone number?
- The practice phone number listed in the NPPES registry for Mary Ann Trephan is (818) 885-8500.
- Does Mary Ann Trephan accept Medicare?
- Mary Ann Trephan is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Mary Ann Trephan's NPI active?
- Yes — Mary Ann Trephan's NPI (1891752614) is active in the NPPES registry as of the last update on 2021-12-01.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.