Doctor profile · Federal record

Dr. WILLIAM RIESEN, MD

Internal Medicine Physician (CMS: INTERNAL MEDICINE) · MASON CITY, IA

  • NPI 1548377997
  • Accepts Medicare
  • 33 yrs in practice
  • Male
  • Group practice
  • No sanctions

Practice & contact

NPPES Updated May 11, 2026
Primary practice
1010 4TH ST SW STE 305
MASON CITY, IA 504012801
(641) 428-5700
fax (641) 428-2515
Mailing address
621 S ILLINOIS AVE, SUITE 103
MASON CITY, IA 504015489

Credentials & registration

NPPES · NUCC
NPI registered
August 2006 — 20 yrs on file
Profile last updated
July 14, 2025
Year of graduation
1993 — 33 yrs since
Specialty taxonomy
207R00000X — NUCC code
State license (1)
Iowa #31260
Medicaid
IA #4137984

Federal sanctions & exclusions

OIG LEIE Updated May 11, 2026

No sanctions, exclusions or revocations on file

Checked against OIG LEIE on NPI 1548377997. Last verified May 11, 2026.

Medicare procedures · 2023

Top services delivered

CMS Provider Utilization
Total services
3,246
Distinct HCPCS
9
Medicare allowed
$154,019
HCPCS Description Services Patients Avg allowed
93010 Routine electrocardiogram (ecg) using at least 12 leads with interpretation and report only 1,406 1,092 $8
99213 Established patient office or other outpatient visit, 20-29 minutes 875 412 $62
99214 Established patient office or other outpatient visit, 30-39 minutes 468 304 $91
99232 Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes 216 64 $73
G0439 Annual wellness visit, includes a personalized prevention plan of service (pps), subsequent visit 186 186 $120
99238 Hospital discharge day management, 30 minutes or less 56 50 $75
99223 Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes 15 15 $162
99204 New patient office or other outpatient visit, 45-59 minutes 13 13 $124
99212 Established patient office or other outpatient visit, 10-19 minutes 11 11 $33

In context: peer comparison

Among 7 peers in this city , average services per provider: 221. This provider delivers 15× the peer median.

Medicare Part D · 2023

Top prescriptions

CMS Part D Prescriber
Total claims
3,142
Patients
805
Total drug cost
$158,873
Drug Type Claims Patients Total cost
Atorvastatin Calcium Generic 428 127 $6,158
Omeprazole Generic 298 72 $3,981
Levothyroxine Sodium Generic 279 76 $3,683
Lisinopril Generic 254 67 $2,157
Losartan Potassium Generic 234 67 $3,022
Metoprolol Succinate Generic 217 60 $3,989
Eliquis (Apixaban) Brand 203 27 $122,997
Gabapentin Generic 200 48 $3,434
Amlodipine Besylate Generic 198 43 $1,287
Hydrochlorothiazide Generic 160 47 $1,242