William I. Parker, MD
Emergency Medicine Physician · Mason City, IA
William I. Parker, MD is an emergency medicine physician with a practice address in Mason City, Iowa, and NPI 1356459903, issued on Aug 25, 2006. Check the license (Iowa 28723, as entered in NPPES) on the Iowa Board of Medicine; the Medicare figures below come from public CMS files.
- Name
- William I. Parker
- Credential
- MD
- Primary taxonomy
- Emergency Medicine Physician 207P00000X
- License number
- 28723 IA
Self-reported in NPPES; status is on the state search - Practice location
- 1000 4TH St SW, Mason City, IA 50401
- Phone
- (641) 422-7234
- Enumerated
- Aug 25, 2006
- Record last updated
- Oct 11, 2023
- Fax
- (641) 422-6373
- Medicaid ID
- 2073189 IA
- Medicare enrollment
- Enrolled (PECOS I20250203003538); accepts Medicare assignment
- Entity
- Type 1 · individual
8 nearest emergency medicine physician records → All 509 in Iowa → Look up another NPI →
Also registered at 1000 4TH St SW
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify William I. Parker in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersIowa Board of Medicine
Search for license 28723Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
20% fewer Medicare Part D claims than the average emergency medicine physician in 2024
180 Medicare Part D claims for 130 beneficiaries, against an average of 226 among the 54,106 providers of this specialty who prescribed in Part D. 38 claims were for opioids.
Most prescribed
- Methylprednisolone21 claims
- Tramadol Hcl19 claims
- Hydrocodone-Acetaminophen18 claims
- Azithromycin16 claims
- Cefdinir11 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Industry payments in 2024: $188.57
2 payments; by number, the most common kind was food and beverage; the largest payer was Boston Scientific Corporation. The 12,335 providers of this specialty with any payment received $953.79 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Bills Medicare through one group practice
- Emergency Medicine Services OF FL LLCLake City, FL
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
William I. Parker among 509 emergency medicine physician records in Iowa
William I. Parker, MD is one of 509 emergency medicine physician records with a practice address in Iowa. 74% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 16% of them.
- NPI issued2006 · 16% of these records are older, 59% newer
- In a Medicare fileYes · 74% of these records are
- In the CMS Doctors and Clinicians fileYes · 45% of these records are
- Graduated1991 · median 2012 among the 231 with a school on file
- Record last updated2023 · 51% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207P00000X and a Iowa practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
12 emergency medicine physician records list a practice address in Mason City
They are 12 of the 866 NPPES records with a practice address in Mason City, and 509 emergency medicine physician records in Iowa.
All 509 in Iowa → Every provider in Mason City → Emergency Medicine Physician nationwide →
The 8 emergency medicine physician records with the nearest ZIP codes
- Gabriel Bensaad-Johnson, DOMason City, IA 504011417538570
- Patricia Endress, DOMason City, IA 504011922116581
- Paul Gordon, MDMason City, IA 504011215043013
- Javeria Iqbal, DOMason City, IA 504011912254038
- Kimberly LovikMason City, IA 504011790130078
- Tavi Madden-Leduc, DOMason City, IA 504011407889272
- Paul Manternach, MDMason City, IA 504011649256272
- Melanie Rajkumar, M.D.Mason City, IA 504011962847434
Common questions
What is William I. Parker, MD's NPI number?
William I. Parker, MD's National Provider Identifier (NPI) is 1356459903, issued on Aug 25, 2006. An NPI identifies a provider in billing; it is not a license.
Where is William I. Parker, MD located?
The NPPES record lists a practice address at 1000 4TH St SW, Mason City, IA, 50401. Phone: (641) 422-7234. Providers update this record themselves, so call before visiting.
How can I verify William I. Parker, MD's license?
NPPES lists Iowa license number 28723, as entered by the provider. Search the Iowa Board of Medicine at https://dial.iowa.gov/about-dial/boards-and-commissions/medicine. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does William I. Parker, MD prescribe under Medicare Part D?
In 2024, William I. Parker, MD had 180 Medicare Part D claims for 130 beneficiaries; the average among emergency medicine physician prescribers was 226. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.