Diana Tsai, MD
NPI 1669534467 · Hospitalist Physician · Mountain View, CA
Enrolled with Medicare as Practitioner - Hospitalist · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Diana Tsai, MD is a Hospitalist Physician provider in Mountain View, CA (NPI 1669534467).
Provider details
- NPI number
- 1669534467
- Entity type
- Individual
- Primary specialty
- Hospitalist PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Female
- Sole proprietor
- No
- License
- A72927 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
19 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
464 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) |
|---|---|---|
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 206 | $89 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 50 Minutes99233 | 81 | $134 |
| Hospital Discharge Day Management, More Than 30 Minutes99239 | 72 | $132 |
| Initial Hospital Care With Moderate Level of Medical Decision Making, If Using Time, at Least 75 Minutes99223 | 67 | $195 |
| Initial Hospital Care With Straightforward Or Low-Level Medical Decision Making, If Using Time, at Least 55 Minutes99222 | 26 | $146 |
| Hospital Discharge Day Management, 30 Minutes Or Less99238 | 12 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 1 distinct drug on file.
| Drug | Part D claims (2024) |
|---|---|
| Cephalexin | 11 |
Medicare Part D only. These counts cover prescriptions paid through Medicare Part D in 2024 — they do notinclude cash-pay, commercial-insurance, Medicaid, or Part B–administered drugs, and badly undercount high cash-pay categories (e.g. GLP-1 weight-loss, testosterone, and ED medications). Any drug with 10 or fewer claims is omitted by CMS, and beneficiary counts under 11 are suppressed — so a missing drug means no Part D record, never zero. This is a factual claims summary, not an endorsement, not medical advice, and not a consumer report. Source: CMS Medicare Part D Prescribers — by Provider and Drug.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-12-15
- Last updated
- 2021-02-25
- Certified
- 2021-02-25
Frequently asked questions
- What is Diana Tsai's NPI number?
- Diana Tsai's National Provider Identifier (NPI) is 1669534467, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Diana Tsai's specialty?
- Diana Tsai is listed in the NPPES registry with a primary specialty of Hospitalist Physician (Allopathic & Osteopathic Physicians).
- Where is Diana Tsai located?
- Diana Tsai's practice location on file with NPPES is 701 E El Camino Real, Mountain View, CA 94040-2833.
- What is Diana Tsai's phone number?
- The practice phone number listed in the NPPES registry for Diana Tsai is (650) 934-7808.
- Does Diana Tsai accept Medicare?
- Diana Tsai is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Diana Tsai's NPI active?
- Yes — Diana Tsai's NPI (1669534467) is active in the NPPES registry as of the last update on 2021-02-25.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.