NPI registry status
Active
2026 NPPES data Family Medicine Physician NPI 1558368043 M.D.
Verify on CMS → Nancy Gryniewicz, M.D.
Family Medicine Physician in Oak Park, Illinois.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 147,760 in Family Medicine Physician, and covers specialty classification, practice address, and Medicare Part D prescribing data when reported. According to CMS, every field reflects the provider's official federal registration, see our methodology.
Federal data, no proprietary rating.
We show these CMS records as-is - no composite score, no star rating, no editorial opinion layered on top.
Prescribing volume
5K
Medicare Part D claims · 355 beneficiaries · Family Medicine Physician avg: 3K
Generic prescribing
83%
generic claims · 16% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$3.3K
145 payments · CMS Open Payments (Sunshine Act)
Source: CMS Medicare Part D Prescriber Public Use File, 2023
What the federal data shows
Nancy Gryniewicz, M.D. filed 4,958 Medicare Part D claims in 2023 as a Family Medicine Physician in Oak Park, Illinois, prescribing 83% generic.
- 5K
- Part D claims, 2023
- 83%
- generic prescribing
- Likely
- board-certified (heuristic)
- ≥94th
- pct by Part D claim volume (lower-bound band)
Every figure on this page comes straight from federal CMS records (NPPES, Medicare Part D, MIPS, Open Payments) - no proprietary rating or editorial opinion is applied.
Nancy Gryniewicz, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
4,958 ≥ 94th percentile 94% of 1,370,886 prescribers are in lower value bands
Each bar is a band; taller bars hold more prescribers. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
The percentile is a conservative 100-claim band: it counts only prescribers in lower claim-volume bands. Medicare Part D claim volume is activity context, not a quality measure or recommendation. See methodology § corpus placement.
Source CMS Medicare Part D Prescriber Public Use File · 2023
✓
Board certification likely (heuristic, not verified)
Nancy Gryniewicz, M.D. practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + 1 hospital affiliation - signals consistent with board-certified status. For verified board certification, see CertificationMatters.org (the official ABMS public lookup).
What does the federal data show about Nancy Gryniewicz, M.D.?
Quality data not reportedPrimary specialty
Family Medicine Physician
Medicare Part D claims
4,958 45% vs specialty avg
Specialty distribution in Illinois
How Family Medicine Physician compares to other specialties among Illinois providers
Board certification
Not published by CMS
CMS does not publish a per-provider board-certification field in NPPES. PlainDoctor does not have a reliable per-specialty certification rate to show for Family Medicine Physician. Verify directly:
How MIPS and board certification work
The Merit-based Incentive Payment System (MIPS) scores providers 0–100 across four performance categories: Quality, Cost, Promoting Interoperability, and Improvement Activities, weighted under 42 CFR §414.1380. Reporting is voluntary for many small practices, so absence of a MIPS score is not a quality signal.
Board certification through an ABMS or AOA member board signals voluntary post-licensure examination plus continuous Maintenance of Certification cycles. Verify any individual provider's status through certificationmatters.org (ABMS) or osteopathic.org (AOA).
Nancy Gryniewicz, M.D. appears in the CMS NPPES registry as a Family Medicine Physician provider holding M.D. credentials at 965 LAKE ST, Oak Park, IL, 60301, with a listed phone of (708) 383-0400. NPI 1558368043 was issued on 06/30/2005.
Medicare Part D records for calendar year 2023 show 4,958 prescription claims written by this provider, covering 355 Medicare beneficiaries and totaling roughly $871K in drug spend, split 16% brand-name and 83% generic by claim count, with an opioid prescribing rate of 1.0%.
Family Medicine Physician is a high-volume specialty nationwide, with 147,760 enrolled providers across 56 states and an average of 3,418 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline.
Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist, always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.
Practice Address
Provider Details
| NPI | 1558368043 |
|---|---|
| Specialty | Family Medicine Physician |
| Credentials | M.D. |
| Gender | Female |
| NPI Issued | 06/30/2005 |
Hospital and facility affiliations
Facilities where Nancy Gryniewicz, M.D. bills Medicare from. Star ratings (1-5) are CMS Hospital Compare's "Hospital overall rating" - a composite of mortality, readmission, patient experience, safety, timely care, and efficient use of medical imaging measures. Source: CMS Care Compare.
Family Medical Care, Ltd
Oak Park, IL
Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).
Industry payments received (2024) - CMS Open Payments transparency data
The federal Physician Payments Sunshine Act (part of the Affordable Care Act) requires drug and medical-device manufacturers + group purchasing organizations to publicly report payments and other transfers of value to physicians and teaching hospitals. The data below covers 2024 for Nancy Gryniewicz, M.D.. Source: openpaymentsdata.cms.gov.
Total received
$3.3K
Largest payer
ABBVIE INC.
Most common payment type
Food and Beverage
Industry payments are not necessarily indicators of bias, they include research funding, consulting fees for evidence-based work, royalties for inventions, food at conferences, and similar items. The disclosure exists for transparency. Read our methodology for how we interpret this data.
License & disciplinary context - Illinois IDFPR 2023 annual report
Aggregate state board data only, NOT a determination of any individual provider's status. The figures below describe statewide disciplinary activity across all ~42K Illinois medical licensees in 2023 - they are NOT specific to Nancy Gryniewicz, M.D.. To verify Nancy Gryniewicz, M.D.'s current license status, search the IDFPR public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.
106
Total board actions, Illinois 2023
Across 103 cases
2.52
Actions per 1,000 licensees
Illinois statewide rate
probation
Most common action type
38 cases
IDFPR publishes annual disciplinary statistics as part of public-record reporting under each state's Administrative Procedure Act. See the full breakdown by action type and year on the Illinois disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.
Brand vs generic prescribing mix · Typical
Nancy Gryniewicz, M.D. - brand share 16.0%
Family Medicine Physician average
16% brand-name claims vs 83% generic, on 4,958 2023 Medicare Part D claims.
The federal Medicare Part D Generic Dispensing Rate national benchmark sits near 90% generic / 10% brand for primary-care prescribers, per CMS Office of the Actuary 2024 estimates. Higher brand share is common in specialty prescribing where generic equivalents are not available.
Medicare Part D Prescribing Data
CMS Medicare Part D prescriber-level data for calendar year 2023.
4,958
Total Claims
$871K
Total Drug Cost
355
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 12,733
- Total Day Supply
- 375,848
- Brand vs Generic
- 16% brand / 83% generic
- Brand Drug Cost
- $774K
- Generic Drug Cost
- $94K
- Opioid Claims
- 52 (1.0% rate)
- Antibiotic Claims
- 100
Patient Demographics
- Average Patient Age
- 74.4 years
- Avg HCC Risk Score
- 1.08
- Gender Split
- 79% female / 21% male
- Age Distribution
- <65: 20, 65-74: 168, 75-84: 126, 85+: 41
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Nancy Gryniewicz, M.D. prescribes most
Top Medicare Part D drugs by claim count, 2023
- Lisinopril
Lisinopril
290 claims
- Amlodipine Besylate
Amlodipine Besylate
276 claims
- Atorvastatin Calcium
Atorvastatin Calcium
266 claims
- Rosuvastatin Calcium
Rosuvastatin Calcium
240 claims
- Simvastatin
Simvastatin
190 claims
- Levothyroxine Sodium
Levothyroxine Sodium
189 claims
- Metformin Hcl
Metformin Hcl
173 claims
- Losartan Potassium
Losartan Potassium
144 claims
| Drug | Claims |
|---|---|
| Lisinopril | 290 |
| Amlodipine Besylate | 276 |
| Atorvastatin Calcium | 266 |
| Rosuvastatin Calcium | 240 |
| Simvastatin | 190 |
| Levothyroxine Sodium | 189 |
| Metformin Hcl | 173 |
| Losartan Potassium | 144 |
| Metoprolol Succinate | 142 |
| Montelukast Sodium | 106 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Family Medicine Physician Overview
How Nancy Gryniewicz, M.D. fits within the Family Medicine Physician landscape nationally.
147,760
Family Medicine Physician Providers in US
56
States with Family Medicine Physician
3,418
Avg Claims per Provider
Nancy Gryniewicz, M.D.'s 4,958 claims are above the specialty average of 3,418.
Nearby Family Medicine Physician Providers in Illinois
Other clinicians with the same primary specialty enrolled in Illinois, drawn from the same CMS NPPES roster as Gryniewicz.
Dr. Jon Aagaard
MD
Wheaton, IL
Dr. Napoleon Abando
MD
Woodstock, IL
Dr. Nikka Abaricia
MD
Chicago, IL
Mohemmed Abbas
Chicago, IL
Muhammad Abbas
Alton, IL
Compare Family Medicine Physician nationally: see state-by-state distribution →
Before you book an appointment
Use this federal record as your verification checklist, not as a recommendation.
- Confirm the NPI record is current in the official CMS registry, providers update their own NPPES details, and moves can lag. Verify this NPI
- Check the active license and any disciplinary history with the Illinois medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Family Medicine Physician peer on Medicare volume and prescribing patterns. Compare providers
Medicare Part D and MIPS figures describe practice patterns in federal programs only, they are not quality ratings, and PlainDoctor does not rate, rank, or recommend providers.
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Medical Specialties Explained
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How insurance networks affect your costs
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Frequently Asked Questions
What is Nancy Gryniewicz, M.D.'s specialty? ▼
Nancy Gryniewicz, M.D. specializes in Family Medicine Physician and practices in Oak Park, Illinois. Credentials: M.D..
How much does Nancy Gryniewicz, M.D. prescribe under Medicare Part D? ▼
In 2023, Nancy Gryniewicz, M.D. wrote 4,958 Medicare Part D claims totaling $871K in drug costs for 355 beneficiaries.
Where is Nancy Gryniewicz, M.D. located? ▼
Nancy Gryniewicz, M.D. is located at 965 LAKE ST, Oak Park, IL, 60301. Phone: (708) 383-0400.
What is Nancy Gryniewicz, M.D.'s NPI number? ▼
Nancy Gryniewicz, M.D.'s National Provider Identifier (NPI) is 1558368043, issued on 06/30/2005.
Does Nancy Gryniewicz, M.D. prescribe more brand-name or generic drugs? ▼
Nancy Gryniewicz, M.D.'s prescribing is 16% brand-name and 83% generic drugs by claim count, with $774K in brand drug costs.
Does Nancy Gryniewicz, M.D. prescribe opioids? ▼
Yes, Nancy Gryniewicz, M.D. had 52 opioid claims in 2023 with an opioid prescribing rate of 1.0%.
How many Family Medicine Physician providers are there in the US? ▼
There are 147,760 Family Medicine Physician providers across 56 states in the US. The average Family Medicine Physician provider writes 3,418 Medicare Part D claims per year.
What drugs does Nancy Gryniewicz, M.D. prescribe most often? ▼
Based on 2023 Medicare Part D data, Nancy Gryniewicz, M.D.'s most frequently prescribed drugs include Lisinopril, Amlodipine Besylate, Atorvastatin Calcium. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Nancy Gryniewicz, M.D. accept Medicare? ▼
Nancy Gryniewicz, M.D. appears in CMS Medicare data with 4,958 Part D claims and 355 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Nancy Gryniewicz, M.D.'s credentials? ▼
Nancy Gryniewicz, M.D.'s NPI is 1558368043 with credentials M.D.. You can verify this through the NPPES NPI Registry, check state medical board records, and confirm board certification through the ABMS or AOA.
Data Sources
View source datasets and methodology notes
- Provider Directory
- CMS National Plan and Provider Enumeration System (NPPES), download.cms.gov/nppes, updated monthly. Contains NPI, specialty, credentials, and practice location.
- Specialty Classification
- NUCC Health Care Provider Taxonomy (nucc.org), the industry standard for classifying provider specialties in Medicare and Medicaid billing.
- Prescribing Data
- CMS Medicare Part D Prescriber Public Use File (2023). Includes claims, drug costs, beneficiaries, and opioid prescribing rates.
- Limitations
- Provider data is self-reported to CMS. Prescribing data reflects Medicare Part D only and does not include commercial insurance, Medicaid, or cash prescriptions. Claims below 11 beneficiaries are suppressed by CMS for privacy.
See our complete data methodology for details on how we collect and process government data.
Data as of April 2026 (NPPES) / 2023 (Medicare Part D). Source: Centers for Medicare & Medicaid Services (CMS).
Disclaimer: Data from CMS NPPES and Medicare Part D. PlainDoctor does not rate or rank providers. Provider information is self-reported and may not be current. Always verify information directly with the provider. About · Methodology
Every figure on PlainDoctor is rendered directly from the federal CMS NPPES registry, Medicare Part D, MIPS, and Open Payments records, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of May 2026.