Allison Zhang, MD
NPI 1821435900 · Gastroenterology Physician · San Jose, CA
Enrolled with Medicare as Practitioner - Gastroenterology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Allison Zhang, MD is a Gastroenterology Physician provider in San Jose, CA (NPI 1821435900).
Provider details
- NPI number
- 1821435900
- Entity type
- Individual
- Primary specialty
- Gastroenterology PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Female
- Sole proprietor
- No
- License
- A165178 (CA)
Specialties & taxonomies
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
13 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
2 documented practice locations
- Medicare service volume (vs. specialty peers)28% of score
931 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) |
|---|---|---|
| Visit Complexity Inherent to Evaluation and Management Associated With Medical Care Services That Serve As the Continuing Focal Point for All Needed Health Care Services And/Or With Medical Care Services That Are Part of Ongoing Care Related to a Patient'SG2211 | 203 | $19 |
| New Patient Office Or Other Outpatient Visit With Moderate Level of Medical Decision Making, If Using Time, 45 Minutes Or More99204 | 154 | $198 |
| Removal of Polyps Or Growths of Large Bowel Using an Endoscope With Mechanical Snare45385 | 132 | $284 |
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 125 | $154 |
| Biopsy of Large Bowel Using a Flexible Endoscope45380 | 124 | $44 |
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 |
|---|---|---|
| Peg3350/Sod Sulf,bicarb,cl/Kclbrand: Gavilyte-G | 152 | 144 |
| Omeprazole | 90 | 41 |
| Peg3350/Sod Sulf,bicarb,cl/Kclbrand: Peg-3350 and Electrolytes | 50 | 49 |
| Sodium, Potassium,mag Sulfatesbrand: Sod Sulf-Potass Sulf-Mag Sulf | 39 | 38 |
| Pantoprazole Sodium | 26 | 11 |
| Esomeprazole Magnesium | 18 | — |
Practice location
Mailing address
Additional practice locations (1)
- 14777 Los Gatos Blvd Ste 200Los Gatos, CA 95032-2059Phone: (669) 294-8800
Registry dates
- Enumerated
- 2013-05-29
- Last updated
- 2024-04-12
- Certified
- 2024-04-12
Frequently asked questions
- What is Allison Zhang's NPI number?
- Allison Zhang's National Provider Identifier (NPI) is 1821435900, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Allison Zhang's specialty?
- Allison Zhang is listed in the NPPES registry with a primary specialty of Gastroenterology Physician (Allopathic & Osteopathic Physicians).
- Where is Allison Zhang located?
- Allison Zhang's practice location on file with NPPES is 2585 Samaritan Dr Ste 25 2nd Fl, San Jose, CA 95124-4107.
- What is Allison Zhang's phone number?
- The practice phone number listed in the NPPES registry for Allison Zhang is (650) 736-5555.
- Does Allison Zhang accept Medicare?
- Allison Zhang is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Allison Zhang's NPI active?
- Yes — Allison Zhang's NPI (1821435900) is active in the NPPES registry as of the last update on 2024-04-12.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.