Karthik Gunachelvan

Primary specialty

Internal Medicine PhysicianTaxonomy code 207R00000X

License

82825 Issued in CT

Practice address

1500 Post Rd Ste 100
Darien, CT 06820-5936

Phone

(203) 655-8749

Fax

(203) 656-0701

NPI assigned

Feb 7, 2014

Sex

Male

Sole proprietor

Yes

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

Specialties & licenses 1

Addresses

Medicare fee-for-service enrollment

Enrolled in MA, CT2 enrollments

Eligible to order & refer

• Part B services: Yes
• Medical equipment: Yes
• Home health: Yes
• Power mobility devices: Yes
• Hospice: Yes

Green means eligible to order or refer.

Enrollment records 2

Specialty

Internal Medicine

Education

Other, 2013

Medicare assignment

Accepts the Medicare-approved amount as payment in full

Telehealth

Offers telehealth services

Group practices

Stamford Health Medical Group IncGroup PAC ID 6901099746, 442 clinicians

Riverbend Medical Group IncGroup PAC ID 5698064343, 227 clinicians

Practice addresses (Care Compare)

Hospital & facility affiliations

• Stamford Hospital Hospital, Stamford, CT, CCN 070006
• Mercy Medical Ctr Hospital, Springfield, MA, CCN 220066
• Baystate Medical Center Hospital, Springfield, MA, CCN 220077

Medicare enrollment (NPD)

Enrolled

Credentials

Doctor of Medicine

State licenses

Practice roles

Locations

Interoperability endpoints

• FHIR API: https://fhir4.healow.com/fhir/r4/ABCIBA

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

• Stamford Health Medical Group Inc

  • General Practice Physician
  • Stamford, CT
  • NPI 1154633980

  Internal Medicine

  Medicare reassignment Care Compare group NPD
• Riverbend Medical Group, Inc.

  dba Trinity Health Of New England Medical Group

  • Internal Medicine Physician
  • Springfield, MA
  • NPI 1841651197
  Medicare reassignment Care Compare group NPD
• Riverbend Medical Group, Inc

  dba Trinity Health Of New England Medical Group

  • Durable Medical Equipment & Medical Supplies
  • Springfield, MA
  • NPI 1265023154
  NPD
• Riverbend Medical Group, Inc

  dba Trinity Health Of New England Medical Group

  • Durable Medical Equipment & Medical Supplies
  • Springfield, MA
  • NPI 1639280779
  NPD (past)

Hospitals and other facilities this clinician is affiliated with according to Medicare Care Compare.

• Stamford Hospital

  • General Acute Care Hospital
  • Stamford, CT
  • NPI 1356331425
  Care Compare affiliation
• Baystate Medical Center Inc

  dba Baystate Medical Center

  • General Acute Care Hospital
  • Springfield, MA
  • NPI 1487655064
  Care Compare affiliation
• Baystate Medical Center Inc

  dba Baystate Reference Laboratories

  • Clinical Medical Laboratory
  • Springfield, MA
  • NPI 1568488450

  Hospital

  Care Compare affiliation
• The Mercy Hospital Inc

  dba Mercy Medical Center

  • General Acute Care Hospital
  • Springfield, MA
  • NPI 1043204316
  Care Compare affiliation
• The Mercy Hospital Inc

  dba Mercy Rehabilitation Hospital

  • Rehabilitation Hospital Unit
  • Springfield, MA
  • NPI 1750360798
  Care Compare affiliation

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

{
    "created_epoch": "1391731200000",
    "enumeration_type": "NPI-1",
    "last_updated_epoch": "1761004800000",
    "number": "1740604941",
    "addresses": [
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "MAILING",
            "address_type": "DOM",
            "address_1": "1500 POST RD STE 100",
            "city": "DARIEN",
            "state": "CT",
            "postal_code": "068205936",
            "telephone_number": "203-655-8749",
            "fax_number": "203-656-0701"
        },
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "LOCATION",
            "address_type": "DOM",
            "address_1": "1500 POST RD STE 100",
            "city": "DARIEN",
            "state": "CT",
            "postal_code": "068205936",
            "telephone_number": "203-655-8749",
            "fax_number": "203-656-0701"
        }
    ],
    "practiceLocations": [],
    "basic": {
        "last_name": "GUNACHELVAN",
        "first_name": "KARTHIK",
        "name_prefix": "Dr.",
        "sole_proprietor": "YES",
        "sex": "M",
        "enumeration_date": "2014-02-07",
        "last_updated": "2025-10-21",
        "certification_date": "2025-10-21",
        "status": "A"
    },
    "taxonomies": [
        {
            "code": "207R00000X",
            "taxonomy_group": "",
            "desc": "Internal Medicine",
            "state": "CT",
            "license": "82825",
            "primary": true
        }
    ],
    "identifiers": [],
    "endpoints": [],
    "other_names": []
}

• Julie Gray
• Greenwich Health PLLC
• Carole N Grenberg, LMFT
• Griebs Darien Pharmacy Inc.
• Nancy Lee Gruener, LPC
• Christine Hahn, LMSW, MBA
• Christine Louise Hamilton-Hall, DMD MD
• Kelly Hanan, RD
• Karen M. Hand, LIC. AC.
• Grace Hanrahan, DPT

• Internal Medicine Physician in Darien, CT
• Providers in Darien, CT by specialty
• Internal Medicine Physician in Connecticut

• NPPES NPI Registry (CMS): identity, addresses, specialties, licenses, identifiers and endpoints. Last updated by the provider on Oct 21, 2025; 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.