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GARY ALTWERGER M.D.
NPI 1407114630
Obstetrics & Gynecology - Gynecologic Oncology in Chicago, IL

Active since April 25, 2012PECOS EnrolledAccepts Medicare Assignment
73.56/100
CMS Quality Rating
5841 S MARYLAND AVE, CHICAGO, IL 60637(888) 824-0200 Get Directions Write a Review

NPPES record last updated: January 15, 2026. Verified against the NPPES registry weekly; last sync: November 01, 2026.

Record update history: Jan 15, 2026, Jun 23, 2016 (2 updates tracked since 2016).

About Gary Altwerger M.d. NPPES

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

GARY ALTWERGER M.D. (NPI 1407114630) is an individual gynecologic oncology provider in Chicago, Illinois, licensed in Illinois (036176993) and active in the NPI registry since April 2012. He is enrolled in Medicare PECOS, is affiliated with Adventist La Grange Memorial Hospital, and maintains 2 additional practice locations.

NPPES Registry Identity

NPI1407114630
Entity TypeIndividualMale
Primary Taxonomy207VX0201X
Provider Legal NameGARY ALTWERGERCredential: M.D.
Location Address5841 S MARYLAND AVEChicago, IL 60637-1443
Mailing Address150 Harvester Dr Ste 300Burr Ridge, IL 60527-5965
Phone(888) 824-0200
Sole ProprietorYes
Medical School CMSOtherGraduated 2012
Enumeration DateApril 25, 2012
Last NPPES UpdateJanuary 15, 20262 updates tracked since enumeration
NPPES CertifiedJanuary 15, 2026
✔ NPI 1407114630 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyObstetrics & Gynecology · Gynecologic OncologyAllopathic & Osteopathic Physicians
Taxonomy Code207VX0201X
License✔ Licensed in IL · 036176993
Definition
An obstetrician/gynecologist who provides consultation and comprehensive management of patients with gynecologic cancer, including those diagnostic and therapeutic procedures necessary for the total care of the patient with gynecologic cancer and resulting complications.
5841 S MARYLAND AVE, Chicago, IL 60637
Open in Google Maps ↗

Secondary Practice Locations 2

Location 1880 W. Central Rd., Suite 5000Arlington Heights, IL 60005-2355 · Phone (847) 618-3800 · Fax (847) 618-3809
Location 2333 cedar street, FMB 328New Haven, CT 06510-3220 · Phone (203) 785-7385 · Fax (203) 785-7134

Accepted Insurance

The full list of accepted plans is on the Insurance tab. Issuers include Ambetter Health, Ambetter Health of Delaware, Oscar Health.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

Gary Altwerger 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 ID2466769849
PECOS Enrollment IDI20251105003308
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

5

Medicare enrollment records show Gary Altwerger reassigns Medicare billing to 5 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

The University Of Chicago Medical Center
Same address
General Acute Care Hospital
5841 S MARYLAND AVE
Chicago, IL 60637
  • Reassigned Medicare billing, Illinois enrollment
  • 1,905 clinicians in this Medicare group
NPI 1033218128 (773) 702-1530
University Of Chicago
Same address
Multi-Specialty
5841 S MARYLAND AVE, UCPG/MC 1099
Chicago, IL 60637
  • Reassigned Medicare billing, Illinois enrollment
  • 2,237 clinicians in this Medicare group
NPI 1821048786 (773) 702-9200
Ahp Specialty Care Nfp
17 mi
Specialist
1 SALT CREEK LN
Hinsdale, IL 60521
  • Reassigned Medicare billing, Illinois enrollment
  • 44 clinicians in this Medicare group
NPI 1619334406 (630) 286-5500
Endeavor Health Medical Group
19 mi
Allergy & Immunology
1000 CENTRAL ST
Evanston, IL 60201
  • Reassigned Medicare billing, Illinois enrollment
  • 4,841 clinicians in this Medicare group
NPI 1497701882 (847) 570-5235
Yale University
760 mi
Adult Mental Health
95 CIRCULAR AVE
Hamden, CT 06514
  • Reassigned Medicare billing, Connecticut enrollment
  • 3,728 clinicians in this Medicare group
NPI 1134391824 (203) 288-6253

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 5

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.

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.
56 services32 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.
31 services15 patients
Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more 99213
This is a routine visit for patients who have already been seen by the healthcare provider. During this approximately 20-29 minute appointment, your health status will be evaluated and any necessary treatments or tests will be discussed. It's a chance to address any health concerns you may have.
17 services15 patients
Telephone medical discussion with physician, 5-10 minutes 99441
A telephone medical discussion with a physician is a brief, 5-10 minute call where you can discuss your health concerns. It's a convenient way to receive medical advice without needing to visit a clinic. It's important to prepare questions in advance to make the most of this time.
16 services14 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.
14 services14 patients

Hospital Affiliations CMS Care Compare 4

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

Adventist La Grange Memorial Hospital

Acute Care Hospitals · La Grange, IL
4/5 CMS rating
OwnershipVoluntary non-profit - Church
CMS Certification Number140065
Location5101 S Willow Springs RdLa Grange, IL 60525 · Cook County
Emergency services

The University Of Chicago Medical Center

Acute Care Hospitals · Chicago, IL
3/5 CMS rating
OwnershipVoluntary non-profit - Private
CMS Certification Number140088
Location5841 South MarylandChicago, IL 60637 · Cook County
Emergency services Birthing friendly

Adventist Hinsdale Hospital

Acute Care Hospitals · Hinsdale, IL
4/5 CMS rating
OwnershipVoluntary non-profit - Private
CMS Certification Number140122
Location120 North Oak StHinsdale, IL 60521 · Du Page County
Emergency services Birthing friendly

Uchicago Medicine Adventhealth Bolingbrook

Acute Care Hospitals · Bolingbrook, IL
4/5 CMS rating
OwnershipVoluntary non-profit - Private
CMS Certification Number140304
Location500 Remington BoulevardBolingbrook, IL 60440 · Will County
Emergency services Birthing friendly

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 60637 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.

New Patient
$183.39 typical visit price
range $60.08 – $183.39
Typical copayment $45.84 (range $15.02 – $45.84)
Most-billed visit code 99205
Established Patient
$105.70 typical visit price
range $18.97 – $148.12
Typical copayment $26.42 (range $4.74 – $37.03)
Most-billed visit code 99214
Amounts reflect what Medicare beneficiaries in this ZIP area are typically charged for office visits. Patients with other coverage should check their individual plans.

Medicare Quality Performance CMS QPP · MIPS

Performance in the CMS Quality Payment Program: the MIPS final score across four weighted categories, and the individual quality measures reported to Medicare.

73.56/100
MIPS Final ScoreMerit-based Incentive Payment System · CMS Quality Payment Program
Scored as part of a group practice
Quality75.84
Promoting Interoperability74
Improvement Activities40
Cost51.43

Referred Medical Equipment & Supplies CMS DME claims 4

Durable medical equipment, devices and supplies this provider ordered from DME suppliers for patients, from Medicare fee-for-service claims.

Parenteral nutrition solution, not otherwise specified, 10 grams lipids B4185
Other-Enteral and Parenteral · category OB005N
1 supplier33 claims809 services$11.30 avg. paid by Medicare
Parenteral nutrition solution; compounded amino acid and carbohydrates with electrolytes, trace elements and vitamins, including preparation, any strength, over 100 grams of protein - premix B4199
Other-Enteral and Parenteral · category OB005N
1 supplier29 claims138 services$321.34 avg. paid by Medicare
Parenteral nutrition supply kit; premix, per day B4220
Other-Enteral and Parenteral · category OB005N
1 supplier30 claims150 services$8.07 avg. paid by Medicare
Parenteral nutrition administration kit, per day B4224
Other-Enteral and Parenteral · category OB005N
1 supplier31 claims156 services$25.19 avg. paid by Medicare
Dollar amounts are the average Medicare paid the supplier per service. They are not the cost to the patient.

Other Providers at the Same Location NPPES 20

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

DR. DON MARTINEZ M.D.
Radiology (Diagnostic Radiology)
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (773) 926-8318
ALEXANDRA DUMITRESCU
Internal Medicine
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (888) 824-0200
PELEG HOROWITZ
Neurological Surgery
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (888) 824-0200
SANDEEP GURBUXANI
Pathology (Hematology)
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (888) 824-0200
DR. NIREN GANDRA M.D.
Internal Medicine
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (773) 702-0240
ALLIE DAKROUB MD MS
Internal Medicine
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (773) 702-1000
SCOTT VASHER MD
Internal Medicine (Pulmonary Disease)
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (773) 702-1000
DR. NATHAN CHARLES NOWALK M.D.
Internal Medicine (Pulmonary Disease)
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (888) 824-0200

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 Gary Altwerger's NPI number?

The NPI number for Gary Altwerger is 1407114630. It was assigned to this individual provider in the NPPES registry on April 25, 2012.

Where is Gary Altwerger located?

Gary Altwerger practices at 5841 S Maryland Ave, Chicago, IL 60637. The listed phone number is (888) 824-0200.

What is Gary Altwerger's specialty?

The primary specialty registered for this NPI is Obstetrics & Gynecology, specializing in Gynecologic Oncology, with taxonomy code 207VX0201X.

Is Gary Altwerger enrolled in Medicare?

Yes. Gary Altwerger 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 Gary Altwerger's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Gary Altwerger reassigns Medicare benefits to 5 organizations: The University Of Chicago Medical Center (Chicago, IL), University Of Chicago (Chicago, IL), Ahp Specialty Care Nfp (Hinsdale, IL), Endeavor Health Medical Group (Evanston, IL) and Yale University (Hamden, CT). 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 Gary Altwerger's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

What insurance does Gary Altwerger accept?

Health plans from Ambetter Health, Ambetter Health of Delaware and Oscar Health list Gary Altwerger 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 Gary Altwerger affiliated with any hospitals?

According to CMS data, Gary Altwerger is affiliated with Adventist La Grange Memorial Hospital, The University Of Chicago Medical Center, Adventist Hinsdale Hospital and Uchicago Medicine Adventhealth Bolingbrook.

When was this NPI record last updated?

The NPPES record for Gary Altwerger was last updated on January 15, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 9 months 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.