Alexander Threlfall, MD
NPI 1669538187 · Psychiatry Physician · Greenbrae, CA
Enrolled with Medicare as Practitioner - Geriatric Psychiatry · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Alexander Threlfall, MD is a Psychiatry Physician provider in Greenbrae, CA (NPI 1669538187).
Provider details
- NPI number
- 1669538187
- Entity type
- Individual
- Primary specialty
- Psychiatry PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- 113086 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
19 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
3 documented practice locations
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 prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 12 distinct drugs on file.
| Drug | Part D claims (2024) |
|---|---|
| Trazodone Hcl | 30 |
| Quetiapine Fumarate | 25 |
| Aripiprazole | 20 |
| Clonazepam | 20 |
| Fluoxetine Hcl | 18 |
| Lorazepam | 18 |
| Lamotrigine | 14 |
| Mirtazapine | 14 |
| Fluvoxamine Maleate | 13 |
Practice location
Mailing address
Additional practice locations (2)
- 5789 State Farm Dr Ste 110Rohnert Park, CA 94928-6308Phone: (707) 615-4437
- 3569 Round Barn CirSanta Rosa, CA 95403-5781Phone: (707) 303-3600
Registry dates
- Enumerated
- 2006-12-29
- Last updated
- 2025-10-29
- Certified
- 2025-10-29
Frequently asked questions
- What is Alexander Threlfall's NPI number?
- Alexander Threlfall's National Provider Identifier (NPI) is 1669538187, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Alexander Threlfall's specialty?
- Alexander Threlfall is listed in the NPPES registry with a primary specialty of Psychiatry Physician (Allopathic & Osteopathic Physicians).
- Where is Alexander Threlfall located?
- Alexander Threlfall's practice location on file with NPPES is 250 Bon Air Rd, Greenbrae, CA 94904-1702.
- What is Alexander Threlfall's phone number?
- The practice phone number listed in the NPPES registry for Alexander Threlfall is (415) 925-7618.
- Does Alexander Threlfall accept Medicare?
- Alexander Threlfall is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Alexander Threlfall's NPI active?
- Yes — Alexander Threlfall's NPI (1669538187) is active in the NPPES registry as of the last update on 2025-10-29.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.