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MATHIAS MASEM, M.D.
NPI 1457371643
Specialist in Oakland, CA

Active since July 20, 2006
80 GRAND AVE.,, SUITE 600, OAKLAND, CA 94612(510) 763-0709(510) 763-8753 Get Directions Write a Review

NPPES record last updated: August 22, 2020. Verified against the NPPES registry weekly; last sync: October 18, 2026.

About Mathias Masem, M.d. NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

MATHIAS MASEM, M.D. (NPI 1457371643) is a healthcare organization registered as a specialist in Oakland, California and active in the NPI registry since July 2006. The organization lists Mathias Masem, Sole Practioner, as its authorized official.

NPPES Registry Identity

NPI1457371643
Entity TypeOrganization
Primary Taxonomy174400000X
Legal Business NameMATHIAS MASEM, M.D.
Location Address80 GRAND AVE.,, SUITE 600Oakland, CA 94612
Mailing Address80 Grand Ave Ste 600Oakland, CA 94612-3744 · (510) 763-0709 · Fax (510) 763-8753
Phone(510) 763-0709
Fax(510) 763-8753
Organization SubpartNo
Authorized OfficialMathias MasemSole Practioner · (510) 763-0709
Enumeration DateJuly 20, 2006
Last NPPES UpdateAugust 22, 2020
✔ NPI 1457371643 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtySpecialistOther Service Providers
Taxonomy Code174400000X
License✔ Licensed in CA · G34134
Definition
An individual educated and trained in an applied knowledge discipline used in the performance of work at a level requiring knowledge and skills beyond or apart from that provided by a general education or liberal arts degree.
80 GRAND AVE.,, Oakland, CA 94612
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Group Practice 1

Group TaxonomyThis provdier is a business group of one or more individual practitioners, all of who practice with the same area of specialization.193400000X SINGLE SPECIALTY GROUP

Medicare Participation & PECOS CMS

Medicare enrollment and the clinicians who bill Medicare through this organization, from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

Mathias Masem, M.d. is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

Clinicians Billing Medicare Through This Organization

3

Medicare enrollment records show 3 clinicians reassign Medicare billing to Mathias Masem, M.D., which bills Medicare for the services they deliver. Of these, 1 practice at this address and 2 within 10 miles. They are listed nearest first.

Clinicians, nearest first (3)

Mathias Masem, M.D.
Orthopedic Surgery
NPI 1508810938
80 GRAND AVE SUITE 600
Oakland, CA 94612
(510) 763-0884
✔ PECOS✔ Accepts MedicareSame address
Gopal Lalchandani, MD
Orthopedic Surgery
NPI 1003279860
1500 OWENS ST STE 200
San Francisco, CA 94158
(415) 353-9400
✔ PECOS✔ Accepts Medicare7.7 mi
Susi Rugama, NP
Nurse Practitioner
NPI 1396078697
300 PASTEUR DR
Stanford, CA 94305
(650) 723-4000
✔ PECOS✔ Accepts Medicare27 mi

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 Mathias Masem, M.D.'s NPI number?

The NPI number for Mathias Masem, M.D. is 1457371643. It was assigned to this organization in the NPPES registry on July 20, 2006.

Where is Mathias Masem, M.D. located?

Mathias Masem, M.D. is located at 80 Grand Ave., Suite 600, Oakland, CA 94612. The listed phone number is (510) 763-0709.

What is Mathias Masem, M.D.'s specialty?

The primary specialty registered for this NPI is Specialist with taxonomy code 174400000X.

Is Mathias Masem, M.D. enrolled in Medicare?

Yes. Mathias Masem, M.D. is registered in the Medicare PECOS enrollment system.

How many clinicians bill Medicare through Mathias Masem, M.D.?

According to the CMS Revalidation Reassignment List (October 2026 release), 3 clinicians reassign their Medicare billing to Mathias Masem, M.D., in Nurse Practitioner and Orthopedic Surgery. 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, 1 practice at this address and 2 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 Mathias Masem, M.D. was last updated on August 22, 2020. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 6 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.