Quick answers
- Which hospitals does Jon S. Portnoff work at?
- Medicare's official clinician data lists Jon S. Portnoff at 5 hospitals: Adventist Health Clearlake, Adventist Health Howard Memorial, Adventist Health Mendocino Coast, Adventist Health St Helena and Adventist Health Ukiah Valley. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Jon S. Portnoff see patients?
- Medicare's clinician data lists 6 practice locations, including Willits, CA, Ukiah, CA and Clearlake, CA. Call before your visit to confirm the address.
- What is Jon S. Portnoff's specialty?
- Medicare lists Cardiovascular Disease (Cardiology) as the primary specialty.
- Does Jon S. Portnoff accept Medicare assignment?
- Yes. Medicare's clinician data says Jon S. Portnoff accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for Jon S. Portnoff?
- (707) 459-6801, as listed in official Medicare / NPI Registry data.
- What is Jon S. Portnoff's NPI number?
- 1609874445. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Jon S. Portnoff works
Medicare's Facility Affiliation Data lists Jon S. Portnoff at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Adventist Health ClearlakeClearlake, CA · Critical Access Hospital · CCN 051317
- Adventist Health Howard MemorialWillits, CA · Critical Access Hospital · CCN 051310
- Adventist Health Mendocino CoastFort Bragg, CA · Critical Access Hospital · CCN 051325
- Adventist Health St HelenaSaint Helena, CA · Acute Care Hospital · CCN 050013
- Adventist Health Ukiah ValleyUkiah, CA · Acute Care Hospital · CCN 050301
Practice locations
Addresses where Jon S. Portnoff is enrolled with Medicare (CMS data updated 2026-10-02). The first 5 of 6; the Medicare profile lists all.
- 1 Marcela DrWillits, CA 95490 (707) 459‑6801
- 115 Hospital DrUkiah, CA 95482 (707) 463‑2400
- 15322 Lakeshore DrClearlake, CA 95422
- 245 Hospital DrUkiah, CA 95482 (707) 462‑3111
- 275 Hospital DrUkiah, CA 95482 (707) 462‑3111
Group practices
Medicare enrollment lists Jon S. Portnoff as a member of these groups (CMS data updated 2026-10-02).
- Adventist Health Physicians Network628 clinicians in the group
- Ukiah Adventist Hospital135 clinicians in the group
- Willits Hospital Inc67 clinicians in the group
Specialties
Find other Cardiovascular Disease (Cardiology) doctors in California →
Other cardiologists in Willits
Clinicians with the same Medicare primary specialty in Willits, CA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 1984 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1609874445 |
| Corrections | Report 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
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians