MACKENZIE ANN OBRIEN NP
NPI 1861123937
Nurse Practitioner - Pediatrics, Critical Care in Palo Alto, CA
About Mackenzie Ann Obrien Np NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
MACKENZIE ANN OBRIEN NP (NPI 1861123937) is an individual pediatrics, critical care provider in Palo Alto, California, licensed in California (95020956) and active in the NPI registry since June 2022. She is enrolled in Medicare PECOS.
NPPES Registry Identity
Specialties & Licenses 2
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare (PECOS)
Mackenzie Ann Obrien Np is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).
Medicare Billing Reassignments
2Medicare enrollment records show Mackenzie Obrien reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Palo Alto, CA 94304
- Reassigned Medicare billing, California enrollment
- 3,617 clinicians in this Medicare group
Stanford, CA 94305
- Reassigned Medicare billing, California enrollment
- 4,258 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Physician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 94304 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
Other Providers at the Same Location NPPES 20
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
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 Mackenzie Obrien's NPI number?
The NPI number for Mackenzie Obrien is 1861123937. It was assigned to this individual provider in the NPPES registry on June 21, 2022.
Where is Mackenzie Obrien located?
Mackenzie Obrien practices at 725 Welch Rd, Palo Alto, CA 94304. The listed phone number is (650) 497-8000.
What is Mackenzie Obrien's specialty?
The primary specialty registered for this NPI is Nurse Practitioner, specializing in Pediatrics, Critical Care, with taxonomy code 363LP0222X.
Is Mackenzie Obrien enrolled in Medicare?
Yes. Mackenzie Obrien is registered in the Medicare PECOS enrollment system.
Which organizations bill Medicare for Mackenzie Obrien's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Mackenzie Obrien reassigns Medicare benefits to 2 organizations: Lpch Medical Group Div Of Lucile (Palo Alto, CA) and Stanford Health Care (Stanford, CA). Each 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 Mackenzie Obrien's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
When was this NPI record last updated?
The NPPES record for Mackenzie Obrien was last updated on September 6, 2023. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 3 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.
# Mackenzie Ann Obrien, NP · NPI 1861123937
Pediatrics, Critical Care physician in Palo Alto, California. Individual provider, active in the CMS NPPES registry since June 21, 2022.
## Identity
- **NPI:** 1861123937 (Entity type: Individual)
- **Enumerated:** June 21, 2022
- **Primary specialty:** Nurse Practitioner - Pediatrics, Critical Care · taxonomy 363LP0222X
- **State license:** 95020956 (California)
- **Sole proprietor:** No
## Practice location
- **Address:** 725 WELCH RD, Palo Alto, CA 94304-1614
- **Phone:** (650) 497-8000
## Medicare
- **Medicare:** Enrolled in Medicare (PECOS)
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 2 organizations under Medicare reassignment (form CMS-855R): Lpch Medical Group Div Of Lucile (NPI 1417907940, Palo Alto, CA); Stanford Health Care (NPI 1437292927, Stanford, CA) · CMS Revalidation Reassignment List, October 2026 release
## Record status
- **NPPES last updated:** September 6, 2023
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Source: [NPI Profile](https://npiprofile.com/npi/1861123937) · Data from the CMS NPPES public registry.