Medical emergency?Emergency? Call 911. Nearest emergency roomsNearest ERs

Emergency Medicine

Kimberly M. Iwaki, MD

Works at hospitals in Antioch, CA · Walnut Creek, CA · California

Summary

Dr. Kimberly M. Iwaki, MD is an emergency medicine doctor at 4501 Sand Creek Rd, Antioch, CA 94531. Phone: (925) 813-6500. Accepts Medicare assignment. In 2024, Kimberly M. Iwaki had 14 Original Medicare patients and 14 services. NPI 1427476266. Source: CMS National Downloadable File, updated October 2, 2026; CMS Facility Affiliation Data, updated October 2, 2026; CMS Medicare Physician & Other Practitioners, data year 2024.

From official Medicare data

This page shows what Medicare's official clinician data says about Kimberly M. Iwaki, joined by NPI number (data updated October 2, 2026). It is not a recommendation or a rating. Call the office or hospital to confirm before you go.

In a medical emergency, call 911.

Quick answers

Does Kimberly M. Iwaki accept Medicare assignment?
Yes. Medicare's clinician data says Kimberly M. Iwaki 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 Kimberly M. Iwaki see?
In 2024, CMS data shows 14 Original Medicare patients and 14 services for Kimberly M. Iwaki. This counts Original Medicare only and measures volume, not quality.
What is Kimberly M. Iwaki's NPI number?
1427476266. 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 Kimberly M. Iwaki, 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 patients14
Services billed to Medicare14
Different services or procedures4
Participating Medicare providerYes
Average age of these patients59

Hospitals where Kimberly M. Iwaki works

Medicare's Facility Affiliation Data lists Kimberly M. Iwaki 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.

Practice locations

Addresses where Kimberly M. Iwaki is enrolled with Medicare (CMS data updated October 2, 2026).

Group practices

Medicare enrollment lists Kimberly M. Iwaki as a member of this group (CMS data updated October 2, 2026).

  • Permanente Medical Group Inc10,996 clinicians in the group

Specialties

Find other Emergency Medicine doctors in California →

Other emergency medicine doctors in Antioch

Clinicians with the same Medicare primary specialty in Antioch, CA — not a recommendation.

All emergency medicine doctors in Antioch →

Other clinicians in Permanente Medical Group Inc

Medicare enrollment lists these clinicians in the same group practice — not a recommendation.

Clinician information

CredentialMD
Medical schoolNorthwestern University Feinberg Medical School
Graduation year2014 (12 years since medical school)
Gender (as listed)Female
Medicare assignmentAccepts (Medicare-approved amount as full payment)
NPI (National Provider Identifier)1427476266
CorrectionsReport 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

  1. Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
  2. Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
  3. National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
  4. Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
  5. NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
  6. Medicare Care Compare — official Medicare tool to look up clinicians