John Gahagan, M.D.
NPI 1558629493 · Surgery Physician · Pleasanton, CA
Enrolled with Medicare as Practitioner - General Surgery · source: CMS PECOS Public Provider Enrollment (2026.04.01)
John Gahagan, M.D. is a Surgery Physician provider in Pleasanton, CA (NPI 1558629493).
Provider details
- NPI number
- 1558629493
- Entity type
- Individual
- Primary specialty
- Surgery PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- A126753 (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
14 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
354 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 | 75 | $137 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 54 | $88 |
| Diagnostic Exam of Anus Using an Endoscope46600 | 51 | $109 |
| New Patient Office Or Other Outpatient Visit With Moderate Level of Medical Decision Making, If Using Time, 45 Minutes Or More99204 | 44 | $177 |
| New Patient Office Or Other Outpatient Visit With a High Level of Medical Decision Making, If Using Time, 60 Minutes Or More99205 | 40 | $239 |
| Initial Hospital Care With Moderate Level of Medical Decision Making, If Using Time, at Least 75 Minutes |
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) | Beneficiaries |
|---|---|---|
| Sodium, Potassium,mag Sulfatesbrand: Sod Sulf-Potass Sulf-Mag Sulf | 24 | 24 |
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
Additional practice locations (1)
- 5800 Hollis StEmeryville, CA 94608-2016Phone: (510) 806-2100
Registry dates
- Enumerated
- 2012-04-29
- Last updated
- 2024-06-11
- Certified
- 2024-06-11
Frequently asked questions
- What is John Gahagan's NPI number?
- John Gahagan's National Provider Identifier (NPI) is 1558629493, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is John Gahagan's specialty?
- John Gahagan is listed in the NPPES registry with a primary specialty of Surgery Physician (Allopathic & Osteopathic Physicians).
- Where is John Gahagan located?
- John Gahagan's practice location on file with NPPES is 5725 W Las Positas Blvd Ste 100, Pleasanton, CA 94588-4007.
- What is John Gahagan's phone number?
- The practice phone number listed in the NPPES registry for John Gahagan is (925) 734-8130.
- Does John Gahagan accept Medicare?
- John Gahagan is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is John Gahagan's NPI active?
- Yes — John Gahagan's NPI (1558629493) is active in the NPPES registry as of the last update on 2024-06-11.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.