William Sim, MD
NPI 1437256906 · Internal Medicine Physician · Downey, CA
Enrolled with Medicare as Practitioner - Internal Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Sim, MD is a Internal Medicine Physician provider in Downey, CA (NPI 1437256906).
Provider details
- NPI number
- 1437256906
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- G72353 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
19 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
4,649 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
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 .
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) |
|---|---|---|
| Residence Visit for Established Patient With Moderate Level of Medical Decision Making, Per Day, If Using Time, at Least 40 Minutes99349 | 1,647 | $134 |
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 677 | $140 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 640 | $99 |
| Residence Visit for Established Patient With Low Level of Medical Decision Making, Per Day, If Using Time, at Least 30 Minutes99348 | 564 | $81 |
| Physician Or Allowed Practitioner Supervision of a Patient Receiving Medicare-Covered Services Provided By a Participating Home Health Agency (patient Not Present) Requiring Complex and Multidisciplinary Care Modalities Involving Regular Physician Or AllowG0181 | 423 | $113 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 275 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Atorvastatin Calcium | 2,063 | 400 |
| Losartan Potassium | 1,669 | 319 |
| Amlodipine Besylate | 1,383 | 265 |
| Metformin Hcl | 1,224 | 243 |
| Levothyroxine Sodium | 1,215 | 245 |
| Metoprolol Succinate | 1,005 | 200 |
| Pantoprazole Sodium |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$1,889 across 88 records (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
- 2006-09-19
- Last updated
- 2011-12-20
Frequently asked questions
- What is William Sim's NPI number?
- William Sim's National Provider Identifier (NPI) is 1437256906, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Sim's specialty?
- William Sim is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is William Sim located?
- William Sim's practice location on file with NPPES is 11480 Brookshire Ave, Downey, CA 90241-9998.
- What is William Sim's phone number?
- The practice phone number listed in the NPPES registry for William Sim is (562) 806-0874.
- Does William Sim accept Medicare?
- William Sim is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Sim's NPI active?
- Yes — William Sim's NPI (1437256906) is active in the NPPES registry as of the last update on 2011-12-20.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.