Katherine Willems, FNP
NPI 1134393069 · Family Nurse Practitioner · Clearlake, CA
Enrolled with Medicare as Practitioner - Nurse Practitioner · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Katherine Willems, FNP is a Family Nurse Practitioner provider in Clearlake, CA (NPI 1134393069).
Provider details
- NPI number
- 1134393069
- Entity type
- Individual
- Primary specialty
- Family Nurse PractitionerPhysician Assistants & Advanced Practice Nursing Providers
- Credential
- FNP
- Sex
- Female
- Sole proprietor
- No
- License
- 404784-7693 (CA)
Specialties & taxonomies
Physician Assistants & Advanced Practice Nursing Providers
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure33% of score
18 yrs in NPPES registry
- Profile completeness33% of score
100% of core fields populated
- Practice footprint20% of score
1 documented practice location
- Open Payments transparency13% of score
Has Open Payments disclosures (2024)
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 52 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Atorvastatin Calcium | 135 | 53 |
| Losartan Potassium | 114 | 40 |
| Amlodipine Besylate | 102 | 36 |
| Levothyroxine Sodium | 96 | 35 |
| Gabapentin | 94 | 35 |
| Lisinopril | 87 | 31 |
| Hydrocodone/Acetaminophen |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$18 across 1 record (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Registry dates
- Enumerated
- 2008-04-22
- Last updated
- 2014-03-04
Frequently asked questions
- What is Katherine Willems's NPI number?
- Katherine Willems's National Provider Identifier (NPI) is 1134393069, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Katherine Willems's specialty?
- Katherine Willems is listed in the NPPES registry with a primary specialty of Family Nurse Practitioner (Physician Assistants & Advanced Practice Nursing Providers).
- Where is Katherine Willems located?
- Katherine Willems's practice location on file with NPPES is 15230 Lakeshore Dr, Clearlake, CA 95422-8107.
- What is Katherine Willems's phone number?
- The practice phone number listed in the NPPES registry for Katherine Willems is (707) 995-4500.
- Does Katherine Willems accept Medicare?
- Katherine Willems is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Katherine Willems's NPI active?
- Yes — Katherine Willems's NPI (1134393069) is active in the NPPES registry as of the last update on 2014-03-04.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.