npidata.org Sign in
Products
Provider RadarWatch an area and specialty — weekly alerts on new cliniciansPractice RadarWeekly alerts when new organisations register nearbySpecialtiesEvery NUCC taxonomy, with counts by state and cityStatesProvider counts and breakdowns for all 50 statesPhysician listsMDs and DOs with addresses and phone numbersNP listsNurse practitioners, the fastest-growing groupAPIJSON, delta feed, free tier
Use cases
Healthcare sales prospectingPhysician recruiting and locum staffingMedical device sales territory planningCredentialing and provider verificationHealthcare marketing lists and audience buildingPharmaceutical sales and prescriber targeting
Account
Start freeThree radars and an export a month Sign in Pricing
Explore
Data Labs API
About
About usTermsPrivacyContact us

Search › Iowa › Internal Medicine Physician

William Riesen, MD

NPI 1548377997 · on the registry since 2006

Practice

Address
1010 4th St Sw Ste 305
Mason City, IA 50401
Phone
(641) 428-5700
Fax
(641) 428-2515
Organisation at this address
North Iowa Mercy Clinics
North Iowa Mercy Clinics
North Iowa Mercy Clinics
North Iowa Mercy Clinics
North Iowa Mercy Clinics
Inferred from a shared address, not stated in the registry.
Clinicians at this address
117

Registry record

Primary taxonomy
Internal Medicine Physician
207R00000X
Licence states on file
IA
From the registry's licence fields, which are often incomplete.
Sex
Male
Record last updated
2025-07-14
Status
Not present in the most recent federal file

Source: CMS National Plan and Provider Enumeration System. Registration is not the same as practising, and the registry records no retirement — some people listed here no longer practise. More in Iowa