Isaiah Mark Horton, MD

Primary specialty

Internal Medicine PhysicianTaxonomy code 207R00000X

License

A200368 Issued in CA

Practice address

245 Terracina Blvd Ste 105
Redlands, CA 92373-4879

Phone

(909) 335-4102

NPI assigned

Jun 5, 2018

Sex

Male

Sole proprietor

No

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

Specialties & licenses 2

Addresses

Medicare fee-for-service enrollment

Enrolled in VA, MD, CA3 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 3

Specialty

Internal Medicine

Education

Loma Linda University School of Medicine, 2018

Medicare assignment

Accepts the Medicare-approved amount as payment in full

Group practices

Southern California Permanente Medical GroupGroup PAC ID 6002729175, 11,250 clinicians

Practice addresses (Care Compare)

Hospital & facility affiliations

• Kaiser Foundation Hospital Fontana/Ontario Hospital, Fontana, CA, CCN 050140
• Barstow Community Hospital Hospital, Barstow, CA, CCN 050298

Merit-based Incentive Payment System (MIPS)

Final score

100 of 100Reported as group

Promoting interoperability

100

Improvement activities

40

Merit-based Incentive Payment System (MIPS)

Final score

83.95 of 100Reported as group

Quality

69.91

Promoting interoperability

99

Improvement activities

40

Cost

77.42

Medicare enrollment (NPD)

Enrolled

Credentials

Doctor of Medicine

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 and National Provider Directory roles.

• Southern California Permanente Medical Group

  • Health Maintenance Organization
  • Riverside, CA
  • NPI 1316979834
  Medicare reassignment Care Compare group NPD
• Beaver Medical Group P C

  • Family Medicine Physician
  • Redlands, CA
  • NPI 1649503319

  Internal Medicine

  Medicare reassignment NPD
• Healthcare Partners Affiliates Medical Group

  • Internal Medicine Physician
  • Los Angeles, CA
  • NPI 1659312593
  Medicare reassignment NPD
• MCV Associated Physicians

  • Anesthesiology Physician
  • Richmond, VA
  • NPI 1710959457
  Medicare reassignment NPD
• University of Maryland Physicians P.a.

  • Cardiovascular Disease Physician
  • Baltimore, MD
  • NPI 1689623175
  Medicare reassignment NPD
• Beaver Medical Group P C

  • Physical Therapist
  • Redlands, CA
  • NPI 1427090281
  NPD
• Cassidy Medical Group Inc.

  • Multi-Specialty Clinic/Center
  • Vista, CA
  • NPI 1215003470
  NPD
• Centers for Family Medicine GP

  • Family Medicine Physician
  • Los Alamitos, CA
  • NPI 1467598243

  Internal Medicine

  NPD
• Healthcare Partners Affiliates Medical Group

  • Durable Medical Equipment & Medical Supplies
  • Murrieta, CA
  • NPI 1760057269
  NPD
• Southern California Permanente Medical Group

  • Health Maintenance Organization
  • Santa Clarita, CA
  • NPI 1316409410
  NPD
• Southern California Permanente Medical Group

  • Health Maintenance Organization
  • Fontana, CA
  • NPI 1689606196
  NPD
• University of Maryland Physicians P.a.

  • Gastroenterology Physician
  • Largo, MD
  • NPI 1619860194
  NPD

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

• Hospital of Barstow Inc

  • General Acute Care Hospital
  • Barstow, CA
  • NPI 1780655670
  Care Compare affiliation
• Kaiser Foundation Hospitals

  • General Acute Care Hospital
  • Fontana, CA
  • NPI 1356496772
  Care Compare affiliation

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

{
    "created_epoch": "1528156800000",
    "enumeration_type": "NPI-1",
    "last_updated_epoch": "1765929600000",
    "number": "1053803940",
    "addresses": [
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "MAILING",
            "address_type": "DOM",
            "address_1": "PO BOX 35380",
            "city": "LAS VEGAS",
            "state": "NV",
            "postal_code": "891335380",
            "telephone_number": "702-579-3203"
        },
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "LOCATION",
            "address_type": "DOM",
            "address_1": "245 TERRACINA BLVD STE 105",
            "city": "REDLANDS",
            "state": "CA",
            "postal_code": "923734879",
            "telephone_number": "909-335-4102"
        }
    ],
    "practiceLocations": [
        {
            "address_1": "Walter Reed National Military Medical Center",
            "address_purpose": "LOCATION",
            "city": "Bethesda",
            "state": "MD",
            "postal_code": "208890001",
            "country_code": "US",
            "telephone_number": "301-295-4900",
            "country_name": "United States",
            "address_type": "DOM"
        }
    ],
    "basic": {
        "last_name": "HORTON",
        "first_name": "ISAIAH",
        "middle_name": "MARK",
        "credential": "MD",
        "sole_proprietor": "NO",
        "sex": "M",
        "enumeration_date": "2018-06-05",
        "last_updated": "2025-12-17",
        "certification_date": "2025-12-17",
        "status": "A"
    },
    "taxonomies": [
        {
            "code": "207R00000X",
            "taxonomy_group": "",
            "desc": "Internal Medicine",
            "state": "VA",
            "license": "0101268175",
            "primary": false
        },
        {
            "code": "207R00000X",
            "taxonomy_group": "",
            "desc": "Internal Medicine",
            "state": "CA",
            "license": "A200368",
            "primary": true
        }
    ],
    "identifiers": [],
    "endpoints": [],
    "other_names": []
}

• Melissa Hordynski, MS, CCC-SLP
• Stephen N. Hordynski, MD
• Horrigan Enterprises, Inc., Buchanan House
• Horst R. Rudrich Medical Corporation
• Jonathan W. Horstmann, MD
• Hospice of Desert Oasis, Inc.
• Hospice Solace, Inc.
• Laura Kay-Aguilar Houck, PA-C
• Corie Diane Houlbjerg, PSY.D.
• D'Hahn House

• Internal Medicine Physician in Redlands, CA
• Providers in Redlands, CA by specialty
• Internal Medicine Physician in California

• NPPES NPI Registry (CMS): identity, addresses, specialties, licenses, identifiers and endpoints. Last updated by the provider on Dec 17, 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.