William Larsen
NPI 1356711584 · Medical Physician Assistant · Elk Grove Village, IL
Enrolled with Medicare as Practitioner - Physician Assistant · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Larsen is a Medical Physician Assistant provider in Elk Grove Village, IL (NPI 1356711584).
Provider details
- NPI number
- 1356711584
- Entity type
- Individual
- Primary specialty
- Medical Physician AssistantPhysician Assistants & Advanced Practice Nursing Providers
- Sex
- Male
- Sole proprietor
- No
- License
- 085005642 (IL)
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 tenure28% of score
10 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
2 documented practice locations
- Medicare service volume (vs. specialty peers)28% of score
130 Medicare services, 2024 (ranked within specialty)
Medicare volume is ranked against active providers in the same specialty. 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 does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 100 | $66 |
| Initial Hospital Care With Straightforward Or Low Level of Medical Decision Making, Per Day, If Using Time, at Least 40 Minutes99221 | 18 | $70 |
| Initial Hospital Care With Straightforward Or Low-Level Medical Decision Making, If Using Time, at Least 55 Minutes99222 | 12 | $116 |
Typical Medicare-allowed amounts for these services range $66–$116 (2024). The Medicare-allowed amount is what Medicare recognizes for a service under fee-for-service — a reference figure for 2024, not a price quote and not what you would be billed. Medicare Part B covers roughly an eighth of all NPIs (65+ skew); services with fewer than 11 beneficiaries are suppressed by CMS. Source: CMS Medicare Physician & Other Practitioners, by Provider & Service.
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 1 distinct drug on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Oxycodone Hcl | 14 | 14 |
Medicare Part D only. These counts cover prescriptions paid through Medicare Part D in 2024 — they do notinclude cash-pay, commercial-insurance, Medicaid, or Part B–administered drugs, and badly undercount high cash-pay categories (e.g. GLP-1 weight-loss, testosterone, and ED medications). Any drug with 10 or fewer claims is omitted by CMS, and beneficiary counts under 11 are suppressed — so a missing drug means no Part D record, never zero. This is a factual claims summary, not an endorsement, not medical advice, and not a consumer report. Source: CMS Medicare Part D Prescribers — by Provider and Drug.
Practice location
Mailing address
Additional practice locations (1)
- 5841 S Maryland AveChicago, IL 60637-1443Phone: (773) 702-1000
Registry dates
- Enumerated
- 2015-09-30
- Last updated
- 2024-09-27
- Certified
- 2024-09-27
Frequently asked questions
- What is William Larsen's NPI number?
- William Larsen's National Provider Identifier (NPI) is 1356711584, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Larsen's specialty?
- William Larsen is listed in the NPPES registry with a primary specialty of Medical Physician Assistant (Physician Assistants & Advanced Practice Nursing Providers).
- Where is William Larsen located?
- William Larsen's practice location on file with NPPES is 800 Biesterfield Rd, Elk Grove Village, IL 60007-3361.
- What is William Larsen's phone number?
- The practice phone number listed in the NPPES registry for William Larsen is (847) 437-5500.
- Does William Larsen accept Medicare?
- William Larsen is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Larsen's NPI active?
- Yes — William Larsen's NPI (1356711584) is active in the NPPES registry as of the last update on 2024-09-27.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.