William Johnston, M.D.
NPI 1417366584 · Emergency Medicine Physician · Palo Alto, CA
Enrolled with Medicare as Practitioner - Emergency Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Johnston, M.D. is a Emergency Medicine Physician provider in Palo Alto, CA (NPI 1417366584).
Provider details
- NPI number
- 1417366584
- Entity type
- Individual
- Primary specialty
- Emergency Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- A138944 (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
11 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
5 documented practice locations
- Medicare service volume (vs. specialty peers)28% of score
35 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) |
|---|---|---|
| Emergency Department Visit With Moderate Level of Medical Decision Making99284 | 23 | $134 |
| Emergency Department Visit With High Level of Medical Decision Making99285 | 12 | $193 |
Typical Medicare-allowed amounts for these services range $134–$193 (2024). The Medicare-allowed amount is what Medicare recognizes for a service under fee-for-service — a reference figure for 2024, not a price quote and not what you would be billed. Medicare Part B covers roughly an eighth of all NPIs (65+ skew); services with fewer than 11 beneficiaries are suppressed by CMS. Source: CMS Medicare Physician & Other Practitioners, by Provider & Service.
Practice location
Mailing address
Additional practice locations (4)
- 222 W 39th AveSan Mateo, CA 94403-4364Phone: (650) 573-2222
- 1200 El Camino RealSouth San Francisco, CA 94080-3208Phone: (650) 742-2000
- 30 Prospect AveHackensack, NJ 07601-1914Phone: (551) 996-2000
- 30 Prospect AveHackensack, NJ 07601-1914Phone: (551) 996-2000
Registry dates
- Enumerated
- 2014-08-03
- Last updated
- 2021-08-12
- Certified
- 2021-08-12
Frequently asked questions
- What is William Johnston's NPI number?
- William Johnston's National Provider Identifier (NPI) is 1417366584, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Johnston's specialty?
- William Johnston is listed in the NPPES registry with a primary specialty of Emergency Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is William Johnston located?
- William Johnston's practice location on file with NPPES is 3801 Miranda Ave, Palo Alto, CA 94304-1207.
- What is William Johnston's phone number?
- The practice phone number listed in the NPPES registry for William Johnston is (650) 493-5000.
- Does William Johnston accept Medicare?
- William Johnston is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Johnston's NPI active?
- Yes — William Johnston's NPI (1417366584) is active in the NPPES registry as of the last update on 2021-08-12.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.