Helen Yang, MD
Helen Yang, MD is an Internal Medicine Physician in Castro Valley, CA, registered under NPI 1003270877.
Getting there
Here is what surrounds this office in Castro Valley, based on OpenStreetMap data collected Sep 15, 2026. Parking is available about 1,004 ft away. The nearest transit stop is 701 ft away, served by Castro Valley Boulevard & Stanton Avenue. If you arrive early, there is a coffee shop 0.36 mi away.
Getting here and what is nearby
Transit John Drive & Castro Valley Boulevard 177 ft ~1 min
Parking John Drive Park and Ride 195 ft ~1 min
N. side of Foothill Blvd. at John Dr. (near I-580), CASTRO VALLEY 94546
Coffee Cafe 4 430 ft ~2 min
Hotel Holiday Inn Express 409 ft ~2 min
2419;2421 Castro Valley Boulevard
Parking 3Crosses Church 435 ft ~2 min
N Side Of Foothill Blvd @ John Dr (Near I-580), Castro Valley 94546
Transit John Drive & Foothill Boulevard 461 ft ~2 min
Gas station Castro Valley Union 76 465 ft ~2 min
2445 Castro Valley Boulevard, Castro Valley 94546
Transit Castro Valley Boulevard & Stanton Avenue 701 ft ~3 min
Restaurant Wendy's 675 ft ~3 min
2475 Castro Valley Boulevard, Castro Valley 94546
08:00-22:00
Restaurant McDonald's 714 ft ~3 min
1620 Strobridge Avenue, Castro Valley 94546
24/7
Gas station United Pacific 877 ft ~4 min
2504 Castro Valley Boulevard
Gas station Stop n Save 981 ft ~4 min
20570 Stanton Avenue
Parking 1,004 ft ~4 min
Hotel Comfort Inn 0.22 mi ~5 min
2532 Castro Valley Boulevard, Castro Valley 94546
Coffee Starbucks 0.36 mi ~8 min
2720 Castro Valley Boulevard, Castro Valley 94546
Restaurant Togo's 0.38 mi ~8 min
2731 Castro Valley Boulevard
Hotel Travelers Inn 0.46 mi ~10 min
17290 Foothill Boulevard, Castro Valley 94546
Distances are straight‑line estimates — walking routes may be longer. Hours and phone numbers can change; call ahead to confirm.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| A153680 | CA | Internal Medicine Physician primary |
This provider holds licence A153680 issued in CA. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
- Status
- Approved
- Provider type
- Practitioner - Internal Medicine
- PAC ID
- 6608284179
- Enrollment ID
- I20210421002849
Medicare enrolment is recorded as approved under the provider type Practitioner - Internal Medicine. Being enrolled means the provider can bill Medicare; it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
What Internal Medicine covers
A physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults and the elderly. Internists are trained in the diagnosis and treatment of cancer, infections and diseases affecting the heart, blood, kidneys, joints and digestive, respiratory and vascular systems. They are also trained in the essentials of primary care internal medicine, which incorporates an understanding of disease prevention, wellness, substance abuse, mental health and effective treatment of common problems of the eyes, ears, skin, nervous system and reproductive organs. NUCC Health Care Provider Taxonomy, code 207R00000X
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1003270877 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Apr 7, 2016 |
| Last updated | Apr 29, 2024 |
| Status | Active |
| Sole proprietor | No |
| Gender | Female |
| Credential | MD |
| Practice address |
20642 JOHN DR Castro Valley, CA 94546 (510) 806-2100 Fax (323) 226-2657 |
| Other identifiers |
hy3232267556
· Medicaid (CA) |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 0 | 0 | 3 | 2 | 7 | 0 | 8 | 7 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 0 | 0 | 3 | 4 | 7 | 0 | 8 | 5 |
Sum = 53 · next multiple of 10 = 60 · check digit = 7 · actual last digit = 7
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.