MR. GUILHERME MARMONTEL NASI M.D.
NPI 1639526825
Student in an Organized Health Care Education/Training Program in Boston, MA

Q: What is Guilherme Marmontel Nasi's NPI number?

The NPI number for Guilherme Marmontel Nasi is 1639526825. It was assigned to this individual provider in the NPPES registry on May 18, 2016.

Q: What is Guilherme Marmontel Nasi's specialty?

The primary specialty registered for this NPI is Student in an Organized Health Care Education/Training Program with taxonomy code 390200000X.

Active since May 18, 2016PECOS EnrolledAccepts Medicare Assignment

72 E CONCORD ST RM 703B, BOSTON, MA 02118(617) 638-8902 Get Directions Write a Review

NPPES record last updated: July 22, 2019. Verified against the NPPES registry weekly; last sync: October 18, 2026.

Record update history: Sep 10, 2023, Jul 12, 2023, Jul 22, 2019 and 1 more (4 updates tracked since 2016).

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About Mr. Guilherme Marmontel Nasi M.d. NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

MR. GUILHERME MARMONTEL NASI M.D. (NPI 1639526825) is an individual student in an organized health care education/training program in Boston, Massachusetts, licensed in Massachusetts (278926) and active in the NPI registry since May 2016. He is enrolled in Medicare PECOS, is affiliated with Massachusetts General Hospital, and maintains a secondary practice location in Boston.

NPPES Registry Identity

NPI1639526825

Entity TypeIndividualMale

Primary Taxonomy390200000X

Provider Legal NameMR. GUILHERME MARMONTEL NASICredential: M.D.

Location Address72 E CONCORD ST RM 703BBoston, MA 02118-2642

Mailing Address72 E Concord St Rm 703bBoston, MA 02118-2642 · (617) 638-8902

Phone(617) 638-8902

Sole ProprietorNo

Medical School CMSOtherGraduated 2013

Enumeration DateMay 18, 2016

Last NPPES UpdateJuly 22, 20194 updates tracked since enumeration

✔ NPI 1639526825 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyStudent in an Organized Health Care Education/Training ProgramStudent, Health Care

Taxonomy Code390200000X

License✔ Licensed in MA · 278926

Definition

An individual who is enrolled in an organized health care education/training program leading to a degree, certification, registration, and/or licensure to provide health care.

72 E CONCORD ST RM 703B, Boston, MA 02118

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Secondary Practice Location 1

Location 155 Fruit StBoston, MA 02114-2696 · Phone (617) 724-9254

Accepted Insurance

The full list of accepted plans is on the Insurance tab. Issuers include Anthem Blue Cross and Blue Shield, Harvard Pilgrim Health Care, Taro Health and more.Insurance ›

Medicare Participation & PECOS CMS

Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare and accepts Medicare assignment

Mr. Guilherme Marmontel Nasi M.d. is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.

PECOS PAC ID6002143047

PECOS Enrollment IDI20230725002751, I20231005001850

Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency✔ Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

Medicare Billing Reassignments

Medicare enrollment records show Guilherme Marmontel Nasi reassigns Medicare billing to 3 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

The General Hospital Corporation

1.9 mi

General Acute Care Hospital

55 FRUIT ST, BULFINCH 360
Boston, MA 02114

Reassigned Medicare billing, Massachusetts enrollment
6,234 clinicians in this Medicare group

NPI 1023049236 (617) 726-2000

Massachusetts General Physicians Organization Inc

1.9 mi

Dermatology

55 FRUIT ST, BUL 2
Boston, MA 02114

Reassigned Medicare billing, Massachusetts enrollment
6,360 clinicians in this Medicare group

NPI 1801874573 (617) 724-0287

Wentworth Douglass Physician Corporation

61 mi

Diabetes Educator

10 MEMBERS WAY FL 5
Dover, NH 03820

Reassigned Medicare billing, New Hampshire enrollment
559 clinicians in this Medicare group

NPI 1336751825 (603) 609-6800

Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Areas of Expertise CMS Part B claims 19

Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.

Routine electrocardiogram (ecg) using at least 12 leads with interpretation and report 93000

An electrocardiogram (ECG) is a non-invasive test that records your heart's electrical activity. Using 12 leads attached to your body, it captures data to help identify heart conditions. A doctor interprets the results and provides a report.

240 services164 patients

Routine electrocardiogram (ecg) using at least 12 leads with interpretation and report only 93010

A routine electrocardiogram (ECG) with 12 leads is a simple, non-invasive test that records the electrical activity of your heart. It helps in identifying heart conditions by detecting irregularities in your heart rhythms. The results are interpreted and a report is provided.

149 services133 patients

Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes 99233

Follow-up hospital inpatient care per day typically involves a 35-minute check-up by your healthcare provider. This service includes monitoring your health progress, adjusting your treatment plan if needed, and answering any questions you may have about your condition or care.

146 services60 patients

Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more 99214

This is a routine check-up for patients who have previously visited our clinic. It involves a comprehensive review of your health and any ongoing treatments. The consultation lasts between 30-39 minutes, allowing enough time to discuss any concerns.

142 services110 patients

Ultrasound of heart with color-depicted blood flow, rate, direction and valve function 93306

This is a heart ultrasound, also known as an echocardiogram. It uses sound waves to create pictures of your heart, showing how blood flows through it. The color depicts the blood flow's speed and direction. It also checks the heart's valves to ensure they're working properly.

128 services128 patients

Established patient office or other outpatient visit with high level of medical decision making, if using time, 40 minutes or more 99215

This service involves a follow-up appointment for existing patients, lasting between 40 to 54 minutes. During this time, your healthcare provider will assess your current health status, discuss any changes or concerns, review your treatment plan, and answer any questions you may have.

110 services64 patients

Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes 99232

Follow-up hospital inpatient care involves daily check-ups while you're admitted in the hospital. Typically, a healthcare provider spends about 25 minutes each day reviewing your condition, adjusting treatment if needed, and answering any questions you might have.

50 services33 patients

Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes 99223

Initial hospital inpatient care per day, typically 70 minutes, refers to the daily medical service provided to patients admitted to the hospital. This includes a comprehensive evaluation, diagnosis, treatment plan, and monitoring of your health condition. It ensures your well-being during your hospital stay.

47 services47 patients

Critical care, first 30-74 minutes 99291

Critical care involves immediate and constant attention by a team of specially-trained health professionals. It's for patients with life-threatening conditions, requiring first 30-74 minutes of intense monitoring and treatment.

42 services13 patients

New patient office or other outpatient visit with moderate level of medical decision making, if using time, 45 minutes or more 99204

This is a first-time office or outpatient visit lasting between 45-59 minutes. The healthcare provider evaluates your health, discusses your medical history, and may suggest further tests or treatments. It's an opportunity to ask questions and understand your health better.

40 services40 patients

Office or other outpatient visit for the evaluation and management of established patient that may not require presence of healthcare professional 99211

This service involves an outpatient visit for established patients who may not need direct interaction with a healthcare professional. It could include reviewing test results, monitoring existing conditions, or adjusting treatment plans. It's typically done remotely, ensuring your comfort and convenience.

29 services27 patients

Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes 99222

Initial hospital inpatient care is a service where a healthcare provider spends about 50 minutes per day overseeing your care while you're admitted in the hospital. This includes reviewing your health status, planning your treatment, and ensuring your safety and comfort.

25 services24 patients

Ultrasound of heart, follow-up 93308

A follow-up ultrasound of the heart, also known as an echocardiogram, is a non-invasive test that uses sound waves to create images of your heart. It helps doctors monitor your heart's function and structures after initial assessment or treatment.

23 services22 patients

New patient office or other outpatient visit with a high level of medical decision making, if using time, 60 minutes or more 99205

This is a first-time patient visit where a healthcare professional spends 60-74 minutes with you. It involves a comprehensive evaluation, including your medical history and current health condition. They'll also advise on preventive health measures and formulate a treatment plan if needed.

23 services23 patients

Routine electrocardiogram (ecg) using at least 12 leads with interpretation and report only 93010

14 services14 patients

Exercise or drug-induced heart stress test with electrocardiogram (ecg) with supervision by physician 93016

An exercise or drug-induced heart stress test with ECG involves monitoring your heart's activity while it's under stress, either from exercise or medication. A doctor supervises the entire procedure to ensure safety and accuracy in results. This test helps detect heart problems.

14 services14 patients

Exercise or drug-induced heart stress test with electrocardiogram (ecg) with review by physician 93018

An exercise or drug-induced heart stress test with ECG is a procedure to assess how your heart functions under stress. It can involve exercising or medication to make your heart work harder while an ECG records its activity. A physician reviews the results.

14 services14 patients

Heart rhythm review, and interpretation of continous external ekg over more than 48 hours up to 7 days 93244

A heart rhythm review involves monitoring your heart's electrical activity for more than 48 hours up to 7 days. Using a device called an external EKG, doctors can track your heartbeats to detect irregularities and help diagnose heart conditions.

12 services12 patients

Ultrasound of heart with color-depicted blood flow, rate, direction and valve function 93306

12 services12 patients

Hospital Affiliations CMS Care Compare 5

Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.

Massachusetts General Hospital

Acute Care Hospitals · Boston, MA

5/5 CMS rating

OwnershipVoluntary non-profit - Private

CMS Certification Number220071

Location55 Fruit StreetBoston, MA 02114 · Suffolk County

Emergency services Birthing friendly

Brigham And Women's Hospital

Acute Care Hospitals · Boston, MA

5/5 CMS rating

OwnershipVoluntary non-profit - Private

CMS Certification Number220110

Location75 Francis StreetBoston, MA 02115 · Suffolk County

Emergency services Birthing friendly

Frisbie Memorial Hospital

Acute Care Hospitals · Rochester, NH

2/5 CMS rating

OwnershipProprietary

CMS Certification Number300014

Location11 Whitehall RoadRochester, NH 03867 · Strafford County

Emergency services

Wentworth-Douglass Hospital

Acute Care Hospitals · Dover, NH

4/5 CMS rating

OwnershipVoluntary non-profit - Private

CMS Certification Number300018

Location789 Central AveDover, NH 03820 · Strafford County

Emergency services Birthing friendly

Portsmouth Regional Hospital

Acute Care Hospitals · Portsmouth, NH

3/5 CMS rating

OwnershipProprietary

CMS Certification Number300029

Location333 Borthwick AvePortsmouth, NH 03801 · Rockingham County

Emergency services Birthing friendly

Frequently Asked Questions NPPES & CMS

Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.

What is Guilherme Marmontel Nasi's NPI number?

The NPI number for Guilherme Marmontel Nasi is 1639526825. It was assigned to this individual provider in the NPPES registry on May 18, 2016.

Where is Guilherme Marmontel Nasi located?

Guilherme Marmontel Nasi practices at 72 E Concord St Rm 703B, Boston, MA 02118. The listed phone number is (617) 638-8902.

What is Guilherme Marmontel Nasi's specialty?

The primary specialty registered for this NPI is Student in an Organized Health Care Education/Training Program with taxonomy code 390200000X.

Is Guilherme Marmontel Nasi enrolled in Medicare?

Yes. Guilherme Marmontel Nasi is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.

Which organizations bill Medicare for Guilherme Marmontel Nasi's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Guilherme Marmontel Nasi reassigns Medicare benefits to 3 organizations: The General Hospital Corporation (Boston, MA), Massachusetts General Physicians Organization Inc (Boston, MA) and Wentworth Douglass Physician Corporation (Dover, NH). Each reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Guilherme Marmontel Nasi's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

What insurance does Guilherme Marmontel Nasi accept?

Health plans from Anthem Blue Cross and Blue Shield, Harvard Pilgrim Health Care, Taro Health and WellSense Health Plan list Guilherme Marmontel Nasi as in-network in at least one marketplace plan. Coverage varies by plan and year; verify with the insurer or the provider before a visit.

Is Guilherme Marmontel Nasi affiliated with any hospitals?

According to CMS data, Guilherme Marmontel Nasi is affiliated with Massachusetts General Hospital, Brigham And Women's Hospital, Frisbie Memorial Hospital, Wentworth-Douglass Hospital and Portsmouth Regional Hospital.

When was this NPI record last updated?

The NPPES record for Guilherme Marmontel Nasi was last updated on July 22, 2019. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 7 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.