Dr. Frederick Richard Stack , MD
Internal Medicine โข Sioux City, IA
801 5th St
Sioux City, IA 511011326
This profile restates public CMS/NPPES data; T-MedInfo gives no medical advice — consult a licensed professional, and call 911 for emergencies.
-
Dr. Frederick Stack is listed in NPPES under Internal Medicine.
-
NPI assigned on September 21, 2005; this date does not establish years in practice.
-
Published CMS data list 650 Original Medicare Part B services in 2024.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider and Service, 2024. Published rows only; this is not a quality measure.
-
Published Part B service records, 2024:
- 99232 โ Subsequent hospital care with moderate levelof medical decision making: 420 service units.
- 99239 โ Hospital discharge day management: 122 service units.
- 99223 โ Initial hospital care with moderate level of medical decision making: 44 service units.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider and Service, 2024. Units differ by code; these are not visits or a measure of quality.
CPTยฎ only copyright 2023 American Medical Association. All rights reserved. Service names are shortened from CPT Consumer Friendly Descriptors (CMS data, 2024). CPT notice
See all 5 records in the table ยท Guide: How to read Medicare Part B data
-
Published CMS data list 107 Medicare Part D prescriptions, including refills, in 2024.
Source: CMS, Medicare Part D Prescribers โ by Provider and Drug, 2024. Published rows only; this is not a quality measure.
-
Published Part D records, 2024:
- Prednisone โ 25 prescription fills, including refills.
- Amlodipine Besylate โ 13 prescription fills, including refills.
- Amoxicillin-Clavulanate Potass (Amoxicillin/Potassium Clav) โ 13 prescription fills, including refills.
Source: CMS, Medicare Part D Prescribers โ by Provider and Drug, 2024. Drug names come from pharmacy claims. Listing a drug here is not an endorsement or a recommendation.
See all 8 records in the table ยท Guide: How to read Medicare Part D prescriber data
-
Fewer Medicare Part B services than 60% of clinicians listed under Internal Medicine in Sioux City, IA (2024, 12 clinicians with data). Median for this group: 739. Middle half: 487 to 1,036.
Close to the middle for Medicare Part B services among clinicians listed under Internal Medicine in Iowa (2024, 349 clinicians with data). Median for this group: 756. Middle half: 286 to 2,320.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider and Service, 2024. Billing and prescribing volume is not a quality rating.
-
Medicare Part B services went from 224 in 2020 to 650 in 2024.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider and Service, 2020โ2024.
Practice Location & Contact Primary Location
801 5th St
Sioux City, IA 511011326
Matched by practice address or phone in NPPES. A shared address or phone does not confirm that this clinician works there.
NPPES lists 3 distinct additional practice-address records in Biddeford, ME; Casa Grande, AZ; Great Falls, MT. See the list
Source: CMS NPPES NPI Registry, practice location records; release date unavailable.
CMS Doctors and Clinicians lists 4 distinct group names: Banner-University Medical Group; Benefis Hospitals Inc; Eastern Maine Medical Center and 1 more. See the list
Source: CMS Doctors and Clinicians National Downloadable File, release date unavailable.
Listings do not confirm current availability, employment or a shared ownership network.
Medicare Profile & Education
Source: CMS Doctors and Clinicians National Downloadable File
University Of Nebraska College Of Medicine
1991
What Public CMS Data Show
Internal Medicine: NPPES taxonomy is a reported classification, not proof of board certification.
Medicare patients
253 people with Original Medicare in 2024
It gives a sense of how many people with Medicare this clinician treated that year.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider, 2024.
Medicare-allowed amount
About $60,758 in 2024
The total amount Medicare approved for these services in 2024. It includes what Medicare paid and what patients or their other insurance owed, such as the deductible and coinsurance.
It shows the total cost of this clinician's Original Medicare services under Medicare's fee rules.
What this does not show: Medicare-allowed amount
This is not the clinician's income. Part of it can go to a clinic or group practice, staff, equipment or drugs. It is not the price you will pay.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider and Service, 2024.
Paid by Medicare
About $47,216 in 2024
The part of the Medicare-allowed amount that Medicare itself paid in 2024, after patients' deductibles and coinsurance.
The gap between the allowed amount and this number is roughly what patients and their other insurance paid.
What this does not show: Paid by Medicare
This is not the clinician's income and not a measure of quality.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider and Service, 2024.
30-day fills
118 standardized 30-day fills in 2024
CMS converts prescriptions to 30-day supplies so they can be compared. A 90-day prescription counts as about three 30-day fills.
What this does not show: 30-day fills
It is not a count of patients and not a measure of quality.
Part D drug cost
$604 in 2024
The total cost of these prescriptions in 2024, paid by Medicare drug plans, patients and other payers together.
It shows the total spending on drugs this clinician prescribed, not what any one patient paid.
What this does not show: Part D drug cost
A higher cost often reflects the type of medicines a specialty uses. It is not your out-of-pocket cost and not a measure of quality.
Source: CMS, Medicare Part D Prescribers โ by Provider and Drug, 2024.
Industry payments (Open Payments)
No Open Payments records are listed for this clinician for 2019โ2025.
Years since graduation
35 years (graduated 1991)
CMS Doctors and Clinicians data list 1991 as the year this clinician finished professional school.
It tells you roughly how long ago the clinician finished school.
What this does not show: Years since graduation
It is not the number of years in practice, and more years does not mean better care.
Source: CMS Doctors and Clinicians National Downloadable File.
NPI first issued
2005
The year this clinician's National Provider Identifier (NPI) was issued. An NPI is a unique 10-digit ID that US health care providers use for billing.
What this does not show: NPI first issued
NPIs have been issued only since 2005, so this year is not necessarily when the clinician started practicing.
Source: CMS NPPES NPI Registry.
Accepts Medicare assignment
CMS data list this clinician as accepting Medicare assignment. This means agreeing to take the Medicare-approved amount as full payment for covered services.
With Original Medicare, you usually pay only your deductible and coinsurance, and the office sends the claim to Medicare for you.
Medicare assignment applies to Original Medicare. It does not tell you whether the clinician is in a Medicare Advantage plan's network, accepts other insurance, or is taking new patients.
Source: CMS Doctors and Clinicians; Medicare.gov, โDoes your provider accept Medicare as full payment?โ
No telehealth indicator
CMS shows this indicator only when recent Medicare claims include telehealth services. The clinician may still offer telehealth; ask the office.
Source: CMS, Telehealth Indicator on Medicare Care Compare (fact sheet, January 2023); CMS Doctors and Clinicians.
Enrolled in Medicare (PECOS)
Dr. Stack has a Medicare enrollment record in PECOS, the CMS system clinicians use to enroll so they can bill Medicare or order services for people with Medicare.
It does not show whether the clinician accepts assignment, is in your plan's network, or is taking new patients.
Source: CMS Medicare Fee-For-Service Public Provider Enrollment (PECOS); CMS Order and Referring file.
Can order Medicare-covered services
CMS lists Dr. Stack as eligible to order or refer Medicare Part B clinical laboratory and imaging services, durable medical equipment (DME) and home health services for people with Medicare.
Medicare pays for these items and services only when they are ordered by an eligible clinician.
What this does not show: Can order Medicare-covered services
It does not mean the clinician offers these services directly.
Source: CMS Medicare Fee-For-Service Public Provider Enrollment (PECOS); CMS Order and Referring file.
Compared with the same specialty in Sioux City and Iowa
Billing and prescribing volume is not a quality rating.
Medicare Part B services
Fewer Medicare Part B services than 60% of clinicians listed under Internal Medicine in Sioux City, IA (2024, 12 clinicians with data). Median for this group: 739. Middle half: 487 to 1,036.
Close to the middle for clinicians listed under Internal Medicine in Iowa (2024, 349 clinicians with data). Median for this group: 756. Middle half: 286 to 2,320.
Medicare-allowed amount
A lower Medicare-allowed amount than 60% of clinicians listed under Internal Medicine in Sioux City, IA (2024, 12 clinicians with data). Median for this group: $79,727. Middle half: $49,769 to $101,768.
Close to the middle for clinicians listed under Internal Medicine in Iowa (2024, 349 clinicians with data). Median for this group: $68,034. Middle half: $24,894 to $145,727.
Paid by Medicare
A lower Medicare payment amount than 60% of clinicians listed under Internal Medicine in Sioux City, IA (2024, 12 clinicians with data). Median for this group: $61,677. Middle half: $38,658 to $80,703.
Close to the middle for clinicians listed under Internal Medicine in Iowa (2024, 349 clinicians with data). Median for this group: $51,828. Middle half: $19,616 to $112,186.
Medicare Part D prescriptions
Fewer Part D prescriptions than 60% of clinicians listed under Internal Medicine in Sioux City, IA (2024, 12 clinicians with data). Median for this group: 203. Middle half: 71 to 401.
Fewer Part D prescriptions than 65% of clinicians listed under Internal Medicine in Iowa (2024, 436 clinicians with data). Median for this group: 429. Middle half: 79 to 6,627.
Part D drug cost
A lower Part D drug cost than 60% of clinicians listed under Internal Medicine in Sioux City, IA (2024, 12 clinicians with data). Median for this group: $8,988. Middle half: $418 to $21,222.
A lower Part D drug cost than 80% of clinicians listed under Internal Medicine in Iowa (2024, 436 clinicians with data). Median for this group: $31,354. Middle half: $1,023 to $491,542.
20 active clinicians are listed under Internal Medicine with a practice address in Sioux City, IA (871 in Iowa).
Addresses are self-reported to NPPES and may be out of date.
Telehealth indicator in Sioux City
0% of these 20 clinicians have the CMS telehealth indicator.
55% of these 20 clinicians are listed by CMS as accepting Medicare assignment.
CMS data by year
Changes may reflect reporting, coverage or privacy limits, not changes in care quality.
-
Medicare Part B services
Medicare Part B services increased 190% from 224 in 2020 to 650 in 2024.
- 2020: 224
- 2021: 298
- 2022: 553
- 2023: 822
- 2024: 650
-
Medicare-allowed amount
Medicare-allowed amount increased 110% from $28,948 in 2020 to $60,758 in 2024.
- 2020: $28,948
- 2021: $33,058
- 2022: $54,402
- 2023: $72,116
- 2024: $60,758
-
Paid by Medicare
Paid by Medicare increased 101% from $23,515 in 2020 to $47,216 in 2024.
- 2020: $23,515
- 2021: $26,566
- 2022: $43,393
- 2023: $56,335
- 2024: $47,216
-
Medicare Part D prescriptions
Medicare Part D prescriptions decreased 15% from 126 in 2020 to 107 in 2024.
- 2020: 126
- 2021: 185
- 2022: 210
- 2023: 134
- 2024: 107
-
30-day fills
30-day fills decreased 41% from 202 in 2020 to 118 in 2024.
- 2020: 202
- 2021: 282
- 2022: 316
- 2023: 252
- 2024: 118
-
Part D drug cost
Part D drug cost decreased 82% from $3,421 in 2020 to $604 in 2024.
- 2020: $3,421
- 2021: $2,914
- 2022: $10,856
- 2023: $2,002
- 2024: $604
Sources: CMS Medicare Physician & Other Practitioners (2024), CMS Medicare Part D Prescribers (2024), CMS Doctors and Clinicians, CMS NPPES NPI Registry. Specialty names follow the NUCC Health Care Provider Taxonomy.
Text: T-MedInfo ยท Report an error.
Performed Procedures & Service Volume
CPTยฎ is a registered trademark of the American Medical Association. CPT codes, descriptions and other data only are copyright 2016โ2023 American Medical Association. All rights reserved. Applicable FARS/HHSARS apply. Descriptions of CPT codes are the AMA's CPT Consumer Friendly Descriptors as published by CMS in the Medicare Physician & Other Practitioners โ by Provider and Service data, 2017โ2024; they are plain-language summaries, not for clinical coding or documentation. HCPCS Level II codes and descriptions are from CMS. Fee schedules, relative value units, conversion factors and/or related components are not assigned by the AMA, are not part of CPT, and the AMA is not recommending their use. The AMA does not directly or indirectly practice medicine or dispense medical services. The AMA assumes no liability for data contained or not contained herein.
| HCPCS Code | Services | Patients | Submitted Charge | Medicare Allowed |
|---|---|---|---|---|
|
99232
Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes
|
420 | 161 | $222.16 | $76.41 |
|
99239
Hospital discharge day management, more than 30 minutes
|
122 | 121 | $327.46 | $110.85 |
|
99223
Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes
|
44 | 43 | $749.64 | $166.20 |
|
99222
Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes
|
41 | 41 | $364.93 | $127.15 |
|
99233
Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes
|
23 | 14 | $391.22 | $113.75 |
Source: CMS Part B by Provider and Service, 2024; services under 11 beneficiaries omitted by CMS. Privacy limits
Submitted charges are billed amounts, not a price quote for your visit.
Medicare Part D Prescribing Profile & Medications
Medicare Part D prescriptions filled, including refills, in 2024.
| Brand Name | Generic Name | Prescriptions | Day Supply | Total Cost | Patients |
|---|---|---|---|---|---|
| Prednisone | Prednisone | 25 | 459 | $86.51 | 25 |
| Amlodipine Besylate | Amlodipine Besylate | 13 | 450 | $65.59 | 13 |
| Amoxicillin-Clavulanate Potass | Amoxicillin/Potassium Clav | 13 | 104 | $90.14 | 13 |
| Cefdinir | Cefdinir | 12 | 82 | $169.94 | 12 |
| Doxycycline Hyclate | Doxycycline Hyclate | 11 | 73 | $61.52 | โ |
| Atorvastatin Calcium | Atorvastatin Calcium | 11 | 510 | $43.70 | โ |
| Clopidogrel | Clopidogrel Bisulfate | 11 | 321 | $62.14 | โ |
| Furosemide | Furosemide | 11 | 351 | $24.10 | โ |
Source: CMS Part D by Provider and Drug, 2024; rows below 11 claims omitted by CMS; volume isn’t quality. Privacy limits
Specialties & License Numbers Reported to NPPES
Self-certified to NPPES: 2026-01-28NUCC Taxonomy Code: 207R00000X
A physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults and the elderly. Internists are trained in the diagnosis and treatment of cancer, infections and diseases affecting the heart, blood, kidneys, joints and digestive, respiratory and vascular systems. They are also trained in the essentials of primary care internal medicine, which incorporates an understanding of disease prevention, wellness, substance abuse, mental health and effective treatment of common problems of the eyes, ears, skin, nervous system and reproductive organs.
NUCC Taxonomy Code: 207R00000X
A physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults and the elderly. Internists are trained in the diagnosis and treatment of cancer, infections and diseases affecting the heart, blood, kidneys, joints and digestive, respiratory and vascular systems. They are also trained in the essentials of primary care internal medicine, which incorporates an understanding of disease prevention, wellness, substance abuse, mental health and effective treatment of common problems of the eyes, ears, skin, nervous system and reproductive organs.
NUCC Taxonomy Code: 174400000X
An individual educated and trained in an applied knowledge discipline used in the performance of work at a level requiring knowledge and skills beyond or apart from that provided by a general education or liberal arts degree.
Additional State Medicaid & Healthcare Payer Identifiers
Medicare (PECOS) Enrollment & Ordering Eligibility
Source: CMS PECOSPRACTITIONER - HOSPITALIST
I20230810000561
ME
9638149230
Sources: CMS Provider Enrollment and Order and Referring. Medicare enrollment is a billing status, not an accreditation or quality rating.
Medicare Group Practice Enrollments
Source: CMS Doctors and Clinicians National Downloadable File
Pines Health Services
163 Van Buren Rd, Caribou, ME 047363567
Phone: 2074986921
Benefis Hospitals Inc
1101 26th St S, Great Falls, MT 594055161
Phone: 4064555000
Eastern Maine Medical Center
489 State St, Bangor, ME 044016616
Phone: 2079737000
Banner-University Medical Group
1625 N Campbell Ave, Tucson, AZ 857194330
Phone: 5206940111
Secondary Practice Locations
1821 N Trekell Rd, Suite 6
Casa Grande, AZ 852221705
Phone: 5204211122
1 Medical Center Dr
Biddeford, ME 040059422
Phone: 2072837937
1101 26th St S
Great Falls, MT 594055161
Phone: 4064554694
Clinicians Sharing This Practice Address or Phone
Clinicians sharing this NPPES address, phone or fax; a shared contact does not mean they work together.
Internal Medicine
Doctor of Medicine (M.D.)
Nurse Practitioner
Certified Registered Nurse Practitioner
Internal Medicine - Interventional Cardiology
Doctor of Medicine (M.D.)
Emergency Medicine
Doctor of Medicine (M.D.)
Emergency Medicine
Doctor of Medicine (M.D.)
Physician Assistant
Physician Assistant (Certified)
Career & Practice History Timeline
Changes recorded in monthly NPPES data files: addresses, names, credentials, specialties and NPI status
Internal Medicine (license number reported to NPPES: MT 91977)
Registered at 6909 EAST RAY ROAD #15-114, CHANDLER, AZ 85226 (Tel: 5204211122)
Registered at 801 5TH ST, SIOUX CITY, IA 511011326 (Tel: 7122792010)
NPI status registered as active in NPPES database
Registered at 1821 N TREKELL RD, SUITE 6, CASA GRANDE, AZ 852221705 (Tel: 5204211122)
Registered at 1821 N TREKELL RD, SUITE 6, CASA GRANDE, AZ 852221705 (Tel: 5204211122)
Recorded as FREDERICK STACK, MD
Specialist (license number reported to NPPES: AZ 24459)
First registered as active Individual Practitioner in NPPES Database.
NPI Administrative Meta
Other Internal Medicine Providers in Sioux City
- Dr. Amy Callaghan, DO
- Dr. Shila Simkhada, MD
- Dr. David Lucke, MD
- Dr. Jolynn Bugbee, MD
- Dr. Steven Feeney, MD
- Dr. Craig Bainbridge, MD
Mailing Address
6909 East Ray Road #15-114
Chandler, AZ 85226
Phone: 5204211122