William Riesen, MD
NPI 1548377997 · Internal Medicine Physician · Mason City, IA
Enrolled with Medicare as Practitioner - Internal Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Riesen, MD is a Internal Medicine Physician provider in Mason City, IA (NPI 1548377997).
Provider details
- NPI number
- 1548377997
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- 31260 (IA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
19 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)28% of score
3,848 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) |
|---|---|---|
| Routine Electrocardiogram (ecg) Using at Least 12 Leads With Interpretation and Report Only93010 | 1,895 | $7 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 641 | $61 |
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 527 | $90 |
| Visit Complexity Inherent to Evaluation and Management Associated With Medical Care Services That Serve As the Continuing Focal Point for All Needed Health Care Services And/Or With Medical Care Services That Are Part of Ongoing Care Related to a Patient'SG2211 | 325 | $15 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 182 | $72 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 110 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Atorvastatin Calcium | 435 | 136 |
| Levothyroxine Sodium | 283 | 70 |
| Lisinopril | 270 | 72 |
| Losartan Potassium | 266 | 72 |
| Omeprazole | 233 | 68 |
| Apixabanbrand: Eliquis | 225 | 32 |
| Metoprolol Succinate |
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-08-23
- Last updated
- 2025-07-14
- Certified
- 2025-07-14
Frequently asked questions
- What is William Riesen's NPI number?
- William Riesen's National Provider Identifier (NPI) is 1548377997, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Riesen's specialty?
- William Riesen is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is William Riesen located?
- William Riesen's practice location on file with NPPES is 1010 4th St Sw Ste 305, Mason City, IA 50401-2801.
- What is William Riesen's phone number?
- The practice phone number listed in the NPPES registry for William Riesen is (641) 428-5700.
- Does William Riesen accept Medicare?
- William Riesen is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Riesen's NPI active?
- Yes — William Riesen's NPI (1548377997) is active in the NPPES registry as of the last update on 2025-07-14.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.