Marion Guyer, MD
NPI 1942388749 · Internal Medicine Physician · Greebrae, CA
Enrolled with Medicare as Practitioner - Internal Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Marion Guyer, MD is a Internal Medicine Physician provider in Greebrae, CA (NPI 1942388749).
Provider details
- NPI number
- 1942388749
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Female
- Sole proprietor
- No
- License
- A66859 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
19 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
304 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
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 .
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 | 169 | $153 |
| New Patient Office Or Other Outpatient Visit With a High Level of Medical Decision Making, If Using Time, 60 Minutes Or More99205 | 39 | $259 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 30 | $109 |
| Routine Electrocardiogram (ecg) Using at Least 12 Leads With Interpretation and Report93000 | 19 | $17 |
| Established Patient Office Or Other Outpatient Visit With High Level of Medical Decision Making, If Using Time, 40 Minutes Or More99215 | 19 | $214 |
| Annual Wellness Visit, Includes a Personalized Prevention Plan of Service (pps), Subsequent Visit |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 13 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Atorvastatin Calcium | 36 | 11 |
| Alendronate Sodium | 20 | — |
| Rosuvastatin Calcium | 19 | — |
| Levothyroxine Sodium | 17 | — |
| Losartan Potassium | 17 | — |
| Amlodipine Besylate | 14 | — |
| Tamsulosin Hcl |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$133 across 7 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-11-01
- Last updated
- 2023-10-05
- Certified
- 2023-10-03
Frequently asked questions
- What is Marion Guyer's NPI number?
- Marion Guyer's National Provider Identifier (NPI) is 1942388749, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Marion Guyer's specialty?
- Marion Guyer is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Marion Guyer located?
- Marion Guyer's practice location on file with NPPES is 1300 S. Eliseo, Greebrae, CA 94902-1408.
- What is Marion Guyer's phone number?
- The practice phone number listed in the NPPES registry for Marion Guyer is (415) 461-5552.
- Does Marion Guyer accept Medicare?
- Marion Guyer is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Marion Guyer's NPI active?
- Yes — Marion Guyer's NPI (1942388749) is active in the NPPES registry as of the last update on 2023-10-05.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.