Katherine L. Sieu, RN, NP
Adult Health Nurse Practitioner · Walnut Creek, CA
Katherine L. Sieu, RN, NP is an adult health nurse practitioner with a practice address in Walnut Creek, California, and NPI 1356591085, issued on Sep 30, 2008. Check the license (California 18369, as entered in NPPES) with the California board that licenses this profession; the Medicare figures below come from public CMS files.
- Name
- Katherine L. Sieu
- Credential
- RN, NP
- Primary taxonomy
- Adult Health Nurse Practitioner 363LA2200X
- License number
- 18369 CA
Self-reported in NPPES; status is on the state search - Practice location
- 500 Lennon LN, Walnut Creek, CA 94598
- Phone
- (925) 939-9610
- Enumerated
- Sep 30, 2008
- Record last updated
- Aug 27, 2010 (not updated in 16 years: call before relying on the address or phone)
- Fax
- (925) 939-9630
- Entity
- Type 1 · individual
8 nearest adult health nurse practitioner records → All 1,405 in California → Look up another NPI →
Also registered at 500 Lennon LN
A shared address usually means a shared clinic or building; it does not show who employs whom.
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- Vivian Park, N.P.Adult Health Nurse Practitioner1932533452
Verify Katherine L. Sieu in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWhich California board licenses this profession
Search for license 18369Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
75% fewer Medicare Part D claims than the average adult health nurse practitioner in 2024
315 Medicare Part D claims for 71 beneficiaries, against an average of 1,280 among the 16,937 providers of this specialty who prescribed in Part D. Brand-name drugs were 9% of claims.
Most prescribed
- Letrozole45 claims
- Hydroxyurea32 claims
- Acyclovir28 claims
- Levothyroxine Sodium24 claims
- Pantoprazole Sodium19 claims
- Tamoxifen Citrate17 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Industry payments in 2024: $304.94
12 payments; by number, the most common kind was food and beverage; the largest payer was GlaxoSmithKline, LLC. The 12,291 providers of this specialty with any payment received $946.40 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Katherine L. Sieu among 1,405 adult health nurse practitioner records in California
Katherine L. Sieu, RN, NP is one of 1,405 adult health nurse practitioner records with a practice address in California. 56% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2008, is newer than 30% of them.
- NPI issued2008 · 30% of these records are older, 66% newer
- In a Medicare fileYes · 56% of these records are
- In the CMS Doctors and Clinicians fileNo · 31% of these records are
- Record last updated2010 · 62% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 363LA2200X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Adult Health Nurse Practitioner providers in California
There are 1,405 adult health nurse practitioner records in California.
All 1,405 in California → Every provider in Walnut Creek → Adult Health Nurse Practitioner nationwide →
The 8 adult health nurse practitioner records with the nearest ZIP codes
- Gwendolyn Cashman, N.P.Walnut Creek, CA 945981720057037
- Li Chen, N.P.Walnut Creek, CA 945981336232560
- Laura Davis, N.P.Walnut Creek, CA 945981982936068
- Tricia McNeal, AGNPWalnut Creek, CA 945981902299506
- Kimberly Oja, NPWalnut Creek, CA 945981396245064
- Vivian Park, N.P.Walnut Creek, CA 945981932533452
- Terilyn Voegtle, APRN, BCWalnut Creek, CA 945981063670743
- Zachary Johnston, NPWalnut Creek, CA 945971730075623
Common questions
What is Katherine L. Sieu, RN, NP's NPI number?
Katherine L. Sieu, RN, NP's National Provider Identifier (NPI) is 1356591085, issued on Sep 30, 2008. An NPI identifies a provider in billing; it is not a license.
Where is Katherine L. Sieu, RN, NP located?
The NPPES record lists a practice address at 500 Lennon LN, Walnut Creek, CA, 94598. Phone: (925) 939-9610. Providers update this record themselves, so call before visiting.
How can I verify Katherine L. Sieu, RN, NP's license?
NPPES lists California license number 18369, as entered by the provider. Search the California board that licenses this profession; the NPPES record confirms identity only.
How much does Katherine L. Sieu, RN, NP prescribe under Medicare Part D?
In 2024, Katherine L. Sieu, RN, NP had 315 Medicare Part D claims for 71 beneficiaries; the average among adult health nurse practitioner prescribers was 1,280. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.