Dr. Grisel Mac Williams , MD
Internal Medicine • Hialeah, FL
810 E 39th Pl
Hialeah, FL 330132863
This profile restates public CMS/NPPES data; T-MedInfo gives no medical advice — consult a licensed professional, and call 911 for emergencies.
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Dr. Grisel Mac Williams is listed in NPPES under Internal Medicine.
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NPI assigned on December 7, 2005; this date does not establish years in practice.
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Published CMS data list 397 Original Medicare Part B services in 2024.
Source: CMS, Medicare Physician & Other Practitioners – by Provider and Service, 2024. Published rows only; this is not a quality measure.
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Published Part B service records, 2024:
- 99214 — Established patient outpatient office visit: 176 service units.
- 99490 — Chronic care management services: 155 service units.
- 99215 — Established patient outpatient office visit: 35 service units.
Source: CMS, Medicare Physician & Other Practitioners – by Provider and Service, 2024. Units differ by code; these are not visits or a measure of quality.
CPT® 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 4 records in the table · Guide: How to read Medicare Part B data
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Published CMS data list 6,020 Medicare Part D prescriptions, including refills, in 2024.
Source: CMS, Medicare Part D Prescribers – by Provider and Drug, 2024. Published rows only; this is not a quality measure.
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Published Part D records, 2024:
- Rosuvastatin Calcium — 305 prescription fills, including refills.
- Losartan Potassium — 263 prescription fills, including refills.
- Metoprolol Succinate — 255 prescription fills, including refills.
Source: CMS, Medicare Part D Prescribers – by Provider and Drug, 2024. Drug names come from pharmacy claims. Listing a drug here is not an endorsement or a recommendation.
See all 118 records in the table · Guide: How to read Medicare Part D prescriber data
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Close to the middle for Medicare Part B services among clinicians listed under Internal Medicine in Hialeah, FL (2024, 62 clinicians with data). Median for this group: 372. Middle half: 165 to 775.
Fewer Medicare Part B services than 65% of clinicians listed under Internal Medicine in Florida (2024, 5,815 clinicians with data). Median for this group: 687. Middle half: 277 to 1,489.
Source: CMS, Medicare Physician & Other Practitioners – by Provider and Service, 2024. Billing and prescribing volume is not a quality rating.
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Medicare Part B services went from 369 in 2020 to 397 in 2024.
Source: CMS, Medicare Physician & Other Practitioners – by Provider and Service, 2020–2024.
Practice Location & Contact Primary Location
810 E 39th Pl
Hialeah, FL 330132863
Matched by practice address or phone in NPPES. A shared address or phone does not confirm that this clinician works there.
Medicare Profile & Education
Source: CMS Doctors and Clinicians National Downloadable File
1980
What Public CMS Data Show
Internal Medicine: NPPES taxonomy is a reported classification, not proof of board certification.
Medicare patients
38 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 – by Provider, 2024.
Medicare-allowed amount
About $44,687 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 – by Provider and Service, 2024.
Paid by Medicare
About $33,192 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 – by Provider and Service, 2024.
30-day fills
13,055 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
$619,637 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 – by Provider and Drug, 2024.
Open Payments general payments, program year 2025
All general payments: $296.81 across 15 records.
By nature of payment
- Food and Beverage: $296.81 across 15 records.
Reporting-company totals (3 largest of 5)
- AstraZeneca Pharmaceuticals LP: $149.89 across 7 records.
- Kowa Pharmaceuticals America, Inc.: $59.71 across 3 records.
- Novo Nordisk Inc: $37.49 across 2 records.
A reported payment does not necessarily mean the financial relationship is improper and is not a measure of care quality. Clinicians can review and dispute these records.
Source: Calculated by T-MedInfo from CMS Open Payments general-payment records for program year 2025 (published June 30, 2026).
Years since graduation
46 years (graduated 1980)
CMS Doctors and Clinicians data list 1980 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, “Does your provider accept Medicare as full payment?”
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. Mac Williams 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. Mac Williams 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 Hialeah and Florida
Billing and prescribing volume is not a quality rating.
Medicare Part B services
Close to the middle for clinicians listed under Internal Medicine in Hialeah, FL (2024, 62 clinicians with data). Median for this group: 372. Middle half: 165 to 775.
Fewer Medicare Part B services than 65% of clinicians listed under Internal Medicine in Florida (2024, 5,815 clinicians with data). Median for this group: 687. Middle half: 277 to 1,489.
Medicare-allowed amount
Close to the middle for clinicians listed under Internal Medicine in Hialeah, FL (2024, 62 clinicians with data). Median for this group: $37,345. Middle half: $13,656 to $82,329.
A lower Medicare-allowed amount than 60% of clinicians listed under Internal Medicine in Florida (2024, 5,815 clinicians with data). Median for this group: $68,256. Middle half: $27,620 to $138,398.
Paid by Medicare
Close to the middle for clinicians listed under Internal Medicine in Hialeah, FL (2024, 62 clinicians with data). Median for this group: $28,843. Middle half: $9,199 to $65,489.
A lower Medicare payment amount than 60% of clinicians listed under Internal Medicine in Florida (2024, 5,815 clinicians with data). Median for this group: $52,728. Middle half: $20,807 to $107,475.
Medicare Part D prescriptions
More Part D prescriptions than 60% of clinicians listed under Internal Medicine in Hialeah, FL (2024, 97 clinicians with data). Median for this group: 3,466. Middle half: 335 to 8,505.
More Part D prescriptions than 75% of clinicians listed under Internal Medicine in Florida (2024, 6,545 clinicians with data). Median for this group: 1,318. Middle half: 158 to 5,882.
Part D drug cost
A higher Part D drug cost than 80% of clinicians listed under Internal Medicine in Hialeah, FL (2024, 97 clinicians with data). Median for this group: $236,965. Middle half: $21,558 to $577,253.
A higher Part D drug cost than 80% of clinicians listed under Internal Medicine in Florida (2024, 6,545 clinicians with data). Median for this group: $86,865. Middle half: $8,159 to $434,445.
139 active clinicians are listed under Internal Medicine with a practice address in Hialeah, FL (10,165 in Florida).
Addresses are self-reported to NPPES and may be out of date.
Telehealth indicator in Hialeah
14.4% of these 139 clinicians have the CMS telehealth indicator.
61.9% of these 139 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.
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Medicare Part B services
Medicare Part B services varied from year to year: 369 in 2020 and 397 in 2024.
- 2020: 369
- 2021: 355
- 2022: 311
- 2023: 468
- 2024: 397
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Medicare-allowed amount
Medicare-allowed amount stayed about the same: $45,736 in 2020 and $44,687 in 2024.
- 2020: $45,736
- 2021: $52,988
- 2022: $41,619
- 2023: $49,900
- 2024: $44,687
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Paid by Medicare
Paid by Medicare stayed about the same: $32,255 in 2020 and $33,192 in 2024.
- 2020: $32,255
- 2021: $38,030
- 2022: $30,590
- 2023: $36,065
- 2024: $33,192
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Medicare Part D prescriptions
Medicare Part D prescriptions decreased 32% from 8,811 in 2020 to 6,020 in 2024.
- 2020: 8,811
- 2021: 7,081
- 2022: 6,971
- 2023: 6,481
- 2024: 6,020
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30-day fills
30-day fills decreased 32% from 19,089 in 2020 to 13,055 in 2024.
- 2020: 19,089
- 2021: 15,147
- 2022: 14,724
- 2023: 13,575
- 2024: 13,055
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Part D drug cost
Part D drug cost decreased 31% from $894,411 in 2020 to $619,637 in 2024.
- 2020: $894,411
- 2021: $743,175
- 2022: $650,027
- 2023: $736,297
- 2024: $619,637
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Industry payments (Open Payments)
Industry payments (Open Payments) decreased 71% from $1,026.75 in 2021 to $296.81 in 2025.
- 2021: $1,026.75
- 2022: $691.22
- 2023: $564.93
- 2024: $481.15
- 2025: $296.81
Sources: CMS Medicare Physician & Other Practitioners (2024), CMS Medicare Part D Prescribers (2024), CMS Open Payments (2025), CMS Doctors and Clinicians, CMS NPPES NPI Registry. Specialty names follow the NUCC Health Care Provider Taxonomy.
Text: T-MedInfo · Report an error.
Pharma & Medical Device Financial Disclosures
Payments and other transfers of value that drug and medical device companies reported to CMS Open Payments
Program year 2025 (payments made January 1 – December 31, 2025): 15 records totaling $296.81.
| Manufacturer | Payment Nature | Product | Type | Amount ($) |
|---|---|---|---|---|
| AstraZeneca Pharmaceuticals LP |
Food and Beverage
In-kind items and services
|
AIRSUPRA | General | $28.68 |
| AstraZeneca Pharmaceuticals LP |
Food and Beverage
In-kind items and services
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AIRSUPRA | General | $26.95 |
| AstraZeneca Pharmaceuticals LP |
Food and Beverage
In-kind items and services
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AIRSUPRA | General | $23.80 |
| AstraZeneca Pharmaceuticals LP |
Food and Beverage
In-kind items and services
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AIRSUPRA | General | $23.43 |
| Novo Nordisk Inc |
Food and Beverage
In-kind items and services
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Ozempic | General | $23.22 |
| AstraZeneca Pharmaceuticals LP |
Food and Beverage
In-kind items and services
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AIRSUPRA | General | $22.80 |
| Kowa Pharmaceuticals America, Inc. |
Food and Beverage
In-kind items and services
|
ZORYVE | General | $20.00 |
| Kowa Pharmaceuticals America, Inc. |
Food and Beverage
In-kind items and services
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ZORYVE | General | $20.00 |
| Kowa Pharmaceuticals America, Inc. |
Food and Beverage
In-kind items and services
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ZORYVE | General | $19.71 |
| AstraZeneca Pharmaceuticals LP |
Food and Beverage
In-kind items and services
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AIRSUPRA | General | $19.07 |
| Eli Lilly and Company |
Food and Beverage
In-kind items and services
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MOUNJARO | General | $17.53 |
| Eli Lilly and Company |
Food and Beverage
In-kind items and services
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MOUNJARO | General | $17.13 |
| Abbott Laboratories |
Food and Beverage
In-kind items and services
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FREESTYLE LIBRE 3 | General | $15.06 |
| Novo Nordisk Inc |
Food and Beverage
In-kind items and services
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Rybelsus | General | $14.27 |
| AstraZeneca Pharmaceuticals LP |
Food and Beverage
In-kind items and services
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AIRSUPRA | General | $5.16 |
Source: CMS Open Payments, program year 2025, released June 30, 2026.
Performed Procedures & Service Volume
CPT® is a registered trademark of the American Medical Association. CPT codes, descriptions and other data only are copyright 2016–2023 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 – by Provider and Service data, 2017–2024; 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 |
|---|---|---|---|---|
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99214
Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more
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176 | 35 | $193.86 | $134.36 |
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99490
Chronic care management services, first 20 minutes of clinical staff time directed by health care professional, per calendar month
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155 | 37 | $120.00 | $65.66 |
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99215
Established patient office or other outpatient visit with high level of medical decision making, if using time, 40 minutes or more
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35 | 19 | $200.00 | $190.41 |
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G0439
Annual wellness visit, includes a personalized prevention plan of service (pps), subsequent visit
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31 | 31 | $250.00 | $135.41 |
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 |
|---|---|---|---|---|---|
| Rosuvastatin Calcium | Rosuvastatin Calcium | 305 | 25,574 | $2,239.01 | 93 |
| Losartan Potassium | Losartan Potassium | 263 | 22,059 | $895.60 | 81 |
| Metoprolol Succinate | Metoprolol Succinate | 255 | 21,692 | $1,198.36 | 72 |
| Metformin Hcl | Metformin Hcl | 176 | 12,925 | $465.64 | 52 |
| Famotidine | Famotidine | 166 | 11,917 | $3,328.30 | 63 |
| Prednisone | Prednisone | 163 | 2,768 | $288.68 | 98 |
| Amlodipine Besylate | Amlodipine Besylate | 162 | 14,400 | $568.30 | 56 |
| Omeprazole | Omeprazole | 159 | 10,413 | $3,076.28 | 44 |
| Levothyroxine Sodium | Levothyroxine Sodium | 148 | 11,876 | $783.69 | 46 |
| Fluticasone Propionate | Fluticasone Propionate | 143 | 7,929 | $1,990.86 | 66 |
| Gabapentin | Gabapentin | 123 | 7,335 | $1,446.49 | 40 |
| Atorvastatin Calcium | Atorvastatin Calcium | 114 | 9,880 | $415.70 | 39 |
| Citalopram Hbr | Citalopram Hydrobromide | 110 | 7,234 | $242.15 | 33 |
| Montelukast Sodium | Montelukast Sodium | 107 | 8,457 | $466.90 | 32 |
| Diclofenac Sodium | Diclofenac Sodium | 101 | 1,978 | $2,370.04 | 39 |
| Lisinopril | Lisinopril | 97 | 8,395 | $243.10 | 26 |
| Azithromycin | Azithromycin | 97 | 487 | $184.80 | 79 |
| Metoprolol Tartrate | Metoprolol Tartrate | 94 | 7,966 | $259.78 | 32 |
| Cyclobenzaprine Hcl | Cyclobenzaprine Hcl | 93 | 3,780 | $849.94 | 39 |
| Losartan-Hydrochlorothiazide | Losartan/Hydrochlorothiazide | 92 | 7,991 | $653.76 | 26 |
| Clotrimazole-Betamethasone | Clotrimazole/Betamethasone Dip | 87 | 2,181 | $1,888.92 | 39 |
| Januvia | Sitagliptin Phosphate | 86 | 5,580 | $105,231.85 | 20 |
| Simvastatin | Simvastatin | 82 | 6,970 | $252.35 | 26 |
| Sertraline Hcl | Sertraline Hcl | 82 | 5,520 | $253.79 | 19 |
| Pantoprazole Sodium | Pantoprazole Sodium | 82 | 6,040 | $292.50 | 25 |
(top 25 shown)
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: 2021-01-08NUCC 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 - INTERNAL MEDICINE
I20110714000543
FL
7315125465
Sources: CMS Provider Enrollment and Order and Referring. Medicare enrollment is a billing status, not an accreditation or quality rating.
Clinicians Sharing This Practice Address or Phone
Clinicians sharing this NPPES address, phone or fax; a shared contact does not mean they work together.
Physician Assistant
Physician Assistant (Certified)
Career & Practice History Timeline
Changes recorded in monthly NPPES data files: addresses, names, credentials, specialties and NPI status
Recorded as GRISEL MAC WILLIAMS, MD
NPI status registered as active in NPPES database
Registered at 810 E 39TH PL, HIALEAH, FL 330132863 (Tel: 3056917018)
Registered at 810 E 39 PL., HIALEAH, FL 33013 (Tel: 3056917018)
Recorded as GRISEL MACWILLIAMS, M.D.
Specialist (license number reported to NPPES: FL ME0045706)
First registered as active Individual Practitioner in NPPES Database.
NPI Administrative Meta
Other Internal Medicine Providers in Hialeah
- Dr. Otto Concepcion, MD
- Dr. Daylis Delgado, DO
- Juan Del Rio
- Dr. Otto Secada, MD
- Dr. Ivette Alfonso Silva, MD
- Dr. Luis De Jongh, MD
More public profiles in Florida
Directory navigation, in NPI number order.
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- Jibran Durrani, MD Internal Medicine - Hematology & Oncology · Miami
- Ayesha Ali, MD Internal Medicine · Pembroke Pines
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- Torge Rempe, MD Psychiatry & Neurology - Neurology · Gainesville
- Michael Marrocco, DMD Dentist · North Miami
- Joseph Santoro Physician Assistant · Coral Gables
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- Jared Shenson, MD Otolaryngology · Orlando
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- Patrick Underwood, MD Surgery - Surgical Oncology · Gainesville
Mailing Address
810 E 39 Pl.
Hialeah, FL 33013
Phone: 3056917018