Quick answers
- Does Margaret Riordan accept Medicare assignment?
- Yes. Medicare's clinician data says Margaret Riordan accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Margaret Riordan see?
- In 2024, CMS data shows 35 Original Medicare patients and 69 services for Margaret Riordan. This counts Original Medicare only and measures volume, not quality.
- What is Margaret Riordan's NPI number?
- 1902061955. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Margaret Riordan, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 35 |
|---|---|
| Services billed to Medicare | 69 |
| Different services or procedures | 31 |
| Participating Medicare provider | Yes |
| Average age of these patients | 68 |
Most frequent services
- Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes (99233)21 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High blood pressure75%
- Stroke or mini-stroke66%
- High cholesterol60%
- Arthritis46%
- Diabetes37%
- Depression34%
Hospitals where Margaret Riordan works
Medicare's Facility Affiliation Data lists Margaret Riordan at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- Alameda HospitalAlameda, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050211
- Highland HospitalOakland, CA · Acute Care Hospital · Medicare rating: 1 of 5 stars · Emergency services: listed by Medicare · CCN 050320
Practice locations
Addresses where Margaret Riordan is enrolled with Medicare (CMS data updated October 2, 2026).
- 1411 E 31st StOakland, CA 94602 (510) 437‑4800
Group practices
Medicare enrollment lists Margaret Riordan as a member of this group (CMS data updated October 2, 2026).
- Alameda Health System601 clinicians in the group
Specialties
- Neurosurgeryprimary
Other neurosurgeons in Oakland
Clinicians with the same Medicare primary specialty in Oakland, CA — not a recommendation.
Other clinicians in Alameda Health System
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Iowa, Rj & L Carver College Of Medicine |
| Graduation year | 2008 (18 years since medical school) |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1902061955 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians