WESTERN LABORATORY MEDICAL GROUP
NPI 1871555979
Pathology - Anatomic Pathology & Clinical Pathology in Hayward, CA
About Western Laboratory Medical Group NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
WESTERN LABORATORY MEDICAL GROUP (NPI 1871555979) is a healthcare organization registered as an anatomic pathology & clinical pathology in Hayward, California and active in the NPI registry since April 2006. The organization lists Elizabeth Treynor, Managing Partner, as its authorized official.
NPPES Registry Identity
Specialties & Licenses
Other Names 1
Other Identifiers 2
Group Practice 1
Medicare Participation & PECOS CMS
Medicare enrollment and the clinicians who bill Medicare through this organization, from CMS.
Medicare Enrollment Status
Enrolled in Medicare (PECOS)
Western Laboratory Medical Group is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).
Clinicians Billing Medicare Through This Organization
8Medicare enrollment records show 8 clinicians reassign Medicare billing to Western Laboratory Medical Group, which bills Medicare for the services they deliver. Of these, 4 practice within 10 miles. They are listed nearest first.
Clinicians, nearest first (8)
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Frequently Asked Questions NPPES & CMS
Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.
What is Western Laboratories's NPI number?
The NPI number for Western Laboratories is 1871555979. It was assigned to this organization in the NPPES registry on April 4, 2006. The provider is doing business as Western Laboratory Medical Group.
Where is Western Laboratories located?
Western Laboratories is located at 27200 Calaroga Ave, Hayward, CA 94545. The listed phone number is (510) 264-4035.
What is Western Laboratories's specialty?
The primary specialty registered for this NPI is Pathology, specializing in Anatomic Pathology & Clinical Pathology, with taxonomy code 207ZP0102X.
Is Western Laboratories enrolled in Medicare?
Yes. Western Laboratories is registered in the Medicare PECOS enrollment system.
How many clinicians bill Medicare through Western Laboratories?
According to the CMS Revalidation Reassignment List (October 2026 release), 8 clinicians, all in Pathology, reassign their Medicare billing to Western Laboratories. A reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for the clinician's services. Of these, 4 practice within 10 miles. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
When was this NPI record last updated?
The NPPES record for Western Laboratories was last updated on April 12, 2017. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 9 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.
# Western Laboratory Medical Group · NPI 1871555979
Anatomic Pathology & Clinical Pathology organization in Hayward, California. Organization record, active in the CMS NPPES registry since April 4, 2006.
## Identity
- **NPI:** 1871555979 (Entity type: Organization)
- **Enumerated:** April 4, 2006
- **Primary specialty:** Pathology - Anatomic Pathology & Clinical Pathology · taxonomy 207ZP0102X
- **Legal business name:** Western Laboratories
- **Organization subpart:** No
- **Authorized official:** Elizabeth Treynor, MANAGING PARTNER
## Practice location
- **Address:** 27200 CALAROGA AVE, Hayward, CA 94545-4339
- **Phone:** (510) 264-4035
## Medicare
- **Medicare:** Enrolled in Medicare (PECOS)
- **Clinicians billing through this organization:** 8 clinicians (Pathology) reassign Medicare billing to this organization (form CMS-855R); 4 practice within 10 miles · CMS Revalidation Reassignment List, October 2026 release
## Record status
- **NPPES last updated:** April 12, 2017
- **Other identifiers:** Medicaid GR0014621 (CA); Medicare UPIN ZZZ91921Z (CA)
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Source: [NPI Profile](https://npiprofile.com/npi/1871555979) · Data from the CMS NPPES public registry.