Margaret Mary Grossmayer, APRN, FNP-C

Primary specialty

Nurse PractitionerTaxonomy code 363L00000X

License

209-033129 Issued in IL

Practice address

3310 W Main St Ste 100
St Charles, IL 60175-1024

Phone

(630) 377-2800

Fax

(630) 377-6774

NPI assigned

Sep 5, 2025

Last updated

Sep 21, 2026By the provider in NPPES

Sex

Female

Sole proprietor

No

Registry information is reported by the provider to CMS and is not verified. About this source

Specialties & licenses 1

Addresses

Electronic endpoints 1

Medicare fee-for-service enrollment

Enrolled in IL

Eligible to order & refer

• Part B services: Yes
• Medical equipment: Yes
• Home health: Yes
• Power mobility devices: Yes
• Hospice: No

Green means eligible to order or refer.

Enrollment records 1

Specialty

Nurse Practitioner

Education

Other, 2025

Medicare assignment

Accepts the Medicare-approved amount as payment in full

Group practices

Midwest Express Care 2, IncGroup PAC ID 0547495467, 221 clinicians

Practice addresses (Care Compare)

Medicare enrollment (NPD)

Enrolled

State licenses

Practice roles

Locations

Organizations this provider is connected to: Medicare benefit reassignments (the organization bills Medicare for this provider’s services), Care Compare group memberships, National Provider Directory roles and organizations whose NPPES authorized official is this provider.

• Midwest Express Care 2, Inc

  • Urgent Care Clinic/Center
  • Willowbrook, IL
  • NPI 1548692890

  Single Specialty

  Medicare reassignment Care Compare group NPD
• Midwest Express Care 2, Inc

  dba Midwest Express Clinic

  • Urgent Care Clinic/Center
  • Chicago, IL
  • NPI 1659952554
  NPD

The complete NPPES record for this NPI in the NPI Registry API format.

{
    "created_epoch": "1757030400000",
    "enumeration_type": "NPI-1",
    "last_updated_epoch": "1789948800000",
    "number": "1548140973",
    "addresses": [
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "MAILING",
            "address_type": "DOM",
            "address_1": "PO BOX 713260",
            "city": "CHICAGO",
            "state": "IL",
            "postal_code": "606771260",
            "telephone_number": "630-469-9200"
        },
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "LOCATION",
            "address_type": "DOM",
            "address_1": "3310 W MAIN ST STE 100",
            "city": "ST CHARLES",
            "state": "IL",
            "postal_code": "601751024",
            "telephone_number": "630-377-2800",
            "fax_number": "630-377-6774"
        }
    ],
    "practiceLocations": [],
    "basic": {
        "last_name": "GROSSMAYER",
        "first_name": "MARGARET",
        "middle_name": "MARY",
        "name_prefix": "Ms.",
        "credential": "APRN, FNP-C",
        "sole_proprietor": "NO",
        "sex": "F",
        "enumeration_date": "2025-09-05",
        "last_updated": "2026-09-21",
        "certification_date": "2026-09-21",
        "status": "A"
    },
    "taxonomies": [
        {
            "code": "363L00000X",
            "taxonomy_group": "",
            "desc": "Nurse Practitioner",
            "state": "IL",
            "license": "209-033129",
            "primary": true
        }
    ],
    "identifiers": [],
    "endpoints": [
        {
            "endpointType": "DIRECT",
            "endpointTypeDescription": "Direct Messaging Address",
            "endpoint": "mgrossmayer380082@dulyhealthandcare.direct-ci.com",
            "affiliation": "N",
            "use": "DIRECT",
            "useDescription": "Direct",
            "address_1": "3310 W Main St Ste 100",
            "city": "St Charles",
            "state": "IL",
            "country_code": "US",
            "postal_code": "601751024",
            "country_name": "United States",
            "address_type": "DOM"
        }
    ],
    "other_names": []
}

• Kerry Ann Gremo
• Theresa Grimaldo
• Marissa Nora Groom, MS
• Grosskopf Orthopedic SC
• Jeffrey W Grosskopf, M.D.
• Kailey Grove, SLP
• Growing Awareness Counseling
• Growing Through Life Therapy LLC
• Growing Wellness LLC (Growing Wellness)
• Elijah Grundman, RBT

• Nurse Practitioner in St Charles, IL
• Providers in St Charles, IL by specialty
• Nurse Practitioner in Illinois

• NPPES NPI Registry (CMS): identity, addresses, specialties, licenses, identifiers and endpoints. Last updated by the provider on Sep 21, 2026; self-reported and not verified by CMS. Specialty names from the NUCC taxonomy.
• Medicare enrollment (CMS PECOS): enrollments, PAC IDs and benefit reassignments; Order and Referring.
• Medicare Care Compare (CMS): clinician profile, group practices, facility affiliations, MIPS scores and star ratings.
• National Provider Directory (CMS): practice roles, locations, licenses, networks and endpoints.

Verify at the official NPI Registry.