Quick answers
- Does Gwendolen Y. Chang accept Medicare assignment?
- Yes. Medicare's clinician data says Gwendolen Y. Chang 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 Gwendolen Y. Chang see?
- In 2024, CMS data shows 488 Original Medicare patients and 2,601 services for Gwendolen Y. Chang. This counts Original Medicare only and measures volume, not quality.
- What is Gwendolen Y. Chang's NPI number?
- 1386807402. 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 Gwendolen Y. Chang, 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 | 488 |
|---|---|
| Services billed to Medicare | 2,601 |
| Different services or procedures | 35 |
| Participating Medicare provider | Yes |
| Average age of these patients | 74 |
Most frequent services
- 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's (G2211)387 services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)379 services
- Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes (99233)358 services
- Dialysis services, 4 or more physician visits per month (20 years or older) (90960)258 services
- Chronic care management services, first 20 minutes of clinical staff time directed by health care professional, per calendar month (99490)203 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%
- High cholesterol75%
- Chronic kidney disease75%
- Diabetes67%
- Heart failure49%
- Ischemic heart disease38%
Hospitals where Gwendolen Y. Chang works
Medicare's Facility Affiliation Data lists Gwendolen Y. Chang 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
- Alta Bates Summit Medical CenterOakland, CA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 050043
- Eden Medical CenterCastro Valley, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050488
- Highland HospitalOakland, CA · Acute Care Hospital · Medicare rating: 1 of 5 stars · Emergency services: listed by Medicare · CCN 050320
Practice locations
Addresses where Gwendolen Y. Chang is enrolled with Medicare (CMS data updated October 2, 2026).
- 13851 E 14th St, Suite 206San Leandro, CA 94578 (510) 351‑9373
- 19850 Lake Chabot RdCastro Valley, CA 94546 (510) 881‑1490
Group practices
Medicare enrollment lists Gwendolen Y. Chang as a member of this group (CMS data updated October 2, 2026).
- West Coast Kidney56 clinicians in the group
Specialties
- Nephrologyprimary
Other nephrologists in San Leandro
Clinicians with the same Medicare primary specialty in San Leandro, CA — not a recommendation.
Other clinicians in West Coast Kidney
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Stanford University School Of Medicine |
| Graduation year | 2007 (19 years since medical school) |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1386807402 |
| 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