Quick answers
- Does William J. Karlon accept Medicare assignment?
- Yes. Medicare's clinician data says William J. Karlon 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 William J. Karlon see?
- In 2024, CMS data shows 508 Original Medicare patients and 728 services for William J. Karlon. This counts Original Medicare only and measures volume, not quality.
- What is William J. Karlon's NPI number?
- 1154365088. 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 William J. Karlon, 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 patients | 508 |
|---|---|
| Services billed to Medicare | 728 |
| Different services or procedures | 14 |
| Participating Medicare provider | Yes |
| Average age of these patients | 73 |
Most frequent services
- Flow cytometry technique for dna or cell analysis, 16 or more markers (88189)486 services
- Flow cytometry technique for dna or cell analysis, 9 to 15 markers (88188)111 services
- Molecular pathology procedure; physician interpretation and report (G0452)79 services
- Antibody evaluation, initial single antibody stain procedure (88346)12 services
- Antibody evaluation, each additional single antibody stain procedure (88350)11 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High blood pressure73%
- High cholesterol68%
- Arthritis40%
- Chronic kidney disease37%
- Ischemic heart disease27%
- Diabetes26%
Hospitals where William J. Karlon works
Medicare's Facility Affiliation Data lists William J. Karlon 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.
- UCSF Health Stanyan HospitalSan Francisco, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050457
- UCSF Medical CenterSan Francisco, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050454
Practice locations
Addresses where William J. Karlon is enrolled with Medicare (CMS data updated October 2, 2026).
- 2330 Post StSan Francisco, CA 94115 (415) 476‑4029
- 505 Parnassus AveSan Francisco, CA 94143 (415) 476‑1000
Group practices
Medicare enrollment lists William J. Karlon as a member of this group (CMS data updated October 2, 2026).
- University of California San Francisco1,839 clinicians in the group
Specialties
- Hematologyprimary
- Pathologyalso
Other hematologists in San Francisco
Clinicians with the same Medicare primary specialty in San Francisco, CA — not a recommendation.
Other clinicians in University of California San Francisco
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of California, Irvine, California College Of Medicine |
| Graduation year | 2002 (24 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1154365088 |
| 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 October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- 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