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LOUDOUN INTERNAL MEDICINE ASSOCIATES
NPI 1093839599
Internal Medicine in Leesburg, VA

Active since March 19, 2007CLIA Certified · 3 labs
19450 DEERFIELD AVENUE, SUITE 300, LEESBURG, VA 20176(703) 858-3220(703) 858-3221 Get Directions Write a Review

NPPES record last updated: October 28, 2022. Verified against the NPPES registry weekly; last sync: October 18, 2026.

Record update history: Oct 28, 2022, Sep 22, 2022, Sep 8, 2022 and 1 more (4 updates tracked since 2021).

About Loudoun Internal Medicine Associates NPPES

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

LOUDOUN INTERNAL MEDICINE ASSOCIATES (NPI 1093839599) is a healthcare organization registered as an internal medicine in Leesburg, Virginia and active in the NPI registry since March 2007. The organization holds 3 active CLIA laboratory certificates and lists Mary Beth Tamasy, Ceo, as its authorized official.

NPPES Registry Identity

NPI1093839599
Entity TypeOrganization
Primary Taxonomy207R00000X
Legal Business NameLOUDOUN MEDICAL GROUP, PC
Location Address19450 DEERFIELD AVENUE, SUITE 300Leesburg, VA 20176-6821
Mailing Address224d Cornwall St Nw Ste 403Leesburg, VA 20176-2704 · (703) 737-6001 · Fax (571) 291-9786
Phone(703) 858-3220
Fax(703) 858-3221
Organization SubpartYes
Authorized OfficialMary Beth TamasyCeo · (703) 737-6010
Enumeration DateMarch 19, 2007
Last NPPES UpdateOctober 28, 20224 updates tracked since enumeration
NPPES CertifiedOctober 28, 2022
✔ NPI 1093839599 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyInternal MedicineAllopathic & Osteopathic Physicians
Taxonomy Code207R00000X
Definition
A physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults and the elderly. Internists are trained in the diagnosis and treatment of cancer, infections and diseases affecting the heart, blood, kidneys, joints and digestive, respiratory and vascular systems. They are also trained in the essentials of primary care internal medicine, which incorporates an understanding of disease prevention, wellness, substance abuse, mental health and effective treatment of common problems of the eyes, ears, skin, nervous system and reproductive organs.
19450 DEERFIELD AVENUE, SUITE 300, Leesburg, VA 20176
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Other Names 1

Doing Business AsLoudoun Internal Medicine Associates

Group Practice 1

Group TaxonomyThis provider is a business group of one or more individual practitioners, who practice with different areas of specialization.193200000X MULTI-SPECIALTY GROUP

Medicare Participation & PECOS CMS

Medicare enrollment and the clinicians who bill Medicare through this organization, from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

Loudoun Internal Medicine Associates is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

Clinicians Billing Medicare Through This Organization

291

Medicare enrollment records show 291 clinicians reassign Medicare billing to Loudoun Internal Medicine Associates, which bills Medicare for the services they deliver. Of these, 21 practice at this address and 181 within 10 miles. Listed here are the 20 practicing nearest to this location.

Clinicians by Medicare Specialty 35

Nurse Practitioner82
Family Practice29
Diagnostic Radiology24
Internal Medicine22
Certified Nurse Midwife (CNM)16
Obstetrics/Gynecology13
Urology13
Gastroenterology9
27 other specialties83

Nearest to this location (20)

See all 291
Hena Ahsan, MSN, NP-C
Nurse Practitioner
NPI 1548742133
19450 DEERFIELD AVENUE SUITE 335
Leesburg, VA 20176
(703) 858-3060
✔ PECOS✔ Accepts MedicareSame address
Nauman Akhtar, M.D.
Orthopedic Surgery
NPI 1003017682
19450 DEERFIELD AVENUE, SUITE 200
Leesburg, VA 20176
(571) 209-1875
✔ PECOS✔ Accepts MedicareSame address
Christopher Bourke, D.P.M.
Podiatry
NPI 1225456361
19450 DEERFIELD AVE STE 200
Leesburg, VA 20176
(703) 777-3262
✔ PECOS✔ Accepts MedicareSame address
Yaser Cheema, MD
Interventional Cardiology
NPI 1124209663
19450 DEERFIELD AVENUE, SUITE 325
Leesburg, VA 20176
(703) 202-1111
✔ PECOS✔ Accepts MedicareSame address
Marianne Crowley, FNP-BC
Nurse Practitioner
NPI 1275400210
19450 DEERFIELD AVENUE, SUITE 325
Leesburg, VA 20176
(703) 202-1111
✔ PECOS✔ Accepts MedicareSame address
Catherine Ellis, M.D.
Endocrinology
NPI 1548473150
19450 DEERFIELD AVENUE, SUITE 200
Leesburg, VA 20176
(703) 844-8380
✔ PECOS✔ Accepts MedicareSame address
Thomas Feely, MD
Internal Medicine
NPI 1477722890
19450 DEERFIELD AVENUE, SUITE 300
Leesburg, VA 20176
(703) 858-3220
✔ PECOS✔ Accepts MedicareSame address
Mathew Gavin, MD
Orthopedic Surgery
NPI 1063408391
19450 DEERFIELD AVE STE 200
Leesburg, VA 20176
(571) 209-1875
✔ PECOS✔ Accepts MedicareSame address
Megan George, MSN, APRN, FNP-C
Nurse Practitioner
NPI 1720867781
19450 DEERFIELD AVENUE, SUITE 300
Leesburg, VA 20176
(703) 858-3220
✔ PECOS✔ Accepts MedicareSame address
Yerin Han, NP
Nurse Practitioner
NPI 1467303800
19450 DEERFIELD AVENUE SUITE 200
Leesburg, VA 20176
(703) 844-8380
✔ PECOS✔ Accepts MedicareSame address
Nadeem Khan, MD
Gastroenterology
NPI 1396708392
19450 DEERFIELD AVENUE, SUITE 335
Leesburg, VA 20176
(703) 858-3060
✔ PECOS✔ Accepts MedicareSame address
Richard Kim, MD
Internal Medicine
NPI 1902890981
19450 DEERFIELD AVENUE, SUITE 300
Leesburg, VA 20176
(703) 858-3220
✔ PECOS✔ Accepts MedicareSame address
Robert Lafsky, M.D.
Gastroenterology
NPI 1336124163
19450 DEERFIELD AVENUE, SUITE 335
Leesburg, VA 20176
(703) 858-3060
✔ PECOS✔ Accepts MedicareSame address
Ali Moshirfar, M.D.
Orthopedic Surgery
NPI 1225130966
19450 DEERFIELD AVE STE 300
Leesburg, VA 20176
(703) 723-6774
✔ PECOS✔ Accepts MedicareSame address
Geetha Pillai, MD
Internal Medicine
NPI 1356335301
19450 DEERFIELD AVENUE, SUITE 300
Leesburg, VA 20176
(703) 858-3220
✔ PECOS✔ Accepts MedicareSame address
Meredith Soriano
Nurse Practitioner
NPI 1962034066
19450 DEERFIELD AVENUE, SUITE 300
Leesburg, VA 20176
(703) 723-6774
✔ PECOS✔ Accepts MedicareSame address
Amanda Thacker, FNP
Nurse Practitioner
NPI 1114621810
19450 DEERFIELD AVENUE, SUITE 200
Leesburg, VA 20176
(703) 844-8380
✔ PECOS✔ Accepts MedicareSame address
Ian Wattenmaker, M.D.
Orthopedic Surgery
NPI 1629077854
19450 DEERFIELD AVENUE, SUITE 200
Leesburg, VA 20176
(703) 777-1553
✔ PECOSSame address
Nidhi Gill, M.D.
Internal Medicine
NPI 1790942266
19450 DEERFIELD AVE SUITE 400
Leesburg, VA 20176
(571) 223-5723
✔ PECOS✔ Accepts MedicareSame address
Sandhya Chanda, MD
Internal Medicine
NPI 1043219710
19450 DEERFIELD AVE SUITE 400
Leesburg, VA 20176
(571) 223-5723
✔ PECOS✔ Accepts MedicareSame address
See all 291 clinicians

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

CLIA Laboratory Certificates CMS CLIA 3

Laboratory certificates issued under the Clinical Laboratory Improvement Amendments (CLIA) program, which sets federal quality standards for human laboratory testing in the United States. There is no official CMS crosswalk between CLIA and NPI numbers; these certificates are associated with this NPI by matching facility names, locations and phone numbers in the CMS CLIA registry.

Certificate of Waiver 49D2039767

Loudoun Internal Medicine Associates · Purcellville, VA
Active · expires Apr 16, 2028
CLIA Number49D2039767
Laboratory TypePhysician Office
Certificate Effective DateApril 17, 2026
Certificate Expiration DateApril 16, 2028
Laboratory DirectorRichard Y. Kim
Laboratory Phone(703) 858-3220
Laboratory LocationLoudoun Internal Medicine Associates921 E Main Street - Suite 2D, Purcellville, VA 20132
CLIA data matches this NPI record on: Name Phone
This certificate is issued to a laboratory to perform only waived tests.

Certificate of Waiver 49D0936981

Loudoun Internal Medicine Associates · Lansdowne, VA
Active · expires Mar 8, 2027
CLIA Number49D0936981
Laboratory TypePhysician Office
Certificate Effective DateMarch 9, 2025
Certificate Expiration DateMarch 8, 2027
Laboratory DirectorRichard Y. Kim
Laboratory Phone(703) 858-3220
Laboratory LocationLoudoun Internal Medicine Associates19450 Deerfield Avenue, Suite 300, Lansdowne, VA 20176
CLIA data matches this NPI record on: Name Phone
This certificate is issued to a laboratory to perform only waived tests.

Certificate of Waiver 49D2122487

Loudoun Internal Medicine Associates · Dulles, VA
Active · expires Nov 28, 2026
CLIA Number49D2122487
Laboratory TypePhysician Office
Certificate Effective DateNovember 29, 2024
Certificate Expiration DateNovember 28, 2026
Laboratory DirectorRichard Y. Kim
Laboratory Phone(703) 858-3220
Laboratory LocationLoudoun Internal Medicine Associates24430 Stone Spring Boulevard Suite 275, Dulles, VA 20166
CLIA data matches this NPI record on: Name Phone
This certificate is issued to a laboratory to perform only waived tests.

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 Loudoun Medical Group, PC's NPI number?

The NPI number for Loudoun Medical Group, PC is 1093839599. It was assigned to this organization in the NPPES registry on March 19, 2007. The provider is doing business as Loudoun Internal Medicine Associates.

Where is Loudoun Medical Group, PC located?

Loudoun Medical Group, PC is located at 19450 Deerfield Avenue, Suite 300, Leesburg, VA 20176. The listed phone number is (703) 858-3220.

What is Loudoun Medical Group, PC's specialty?

The primary specialty registered for this NPI is Internal Medicine with taxonomy code 207R00000X.

Is Loudoun Medical Group, PC enrolled in Medicare?

Yes. Loudoun Medical Group, PC is registered in the Medicare PECOS enrollment system.

How many clinicians bill Medicare through Loudoun Medical Group, PC?

According to the CMS Revalidation Reassignment List (October 2026 release), 291 clinicians in 35 Medicare specialties reassign their Medicare billing to Loudoun Medical Group, PC. A 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 the clinician's services. The largest specialties are Nurse Practitioner (82), Family Practice (29) and Diagnostic Radiology (24). Of these, 21 practice at this address and 181 within 10 miles. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Does Loudoun Medical Group, PC hold CLIA laboratory certificates?

Yes. 3 active CLIA laboratory certificates are associated with this NPI under the federal Clinical Laboratory Improvement Amendments program. The certificates are listed in the CLIA Laboratory Certificates section above.

When was this NPI record last updated?

The NPPES record for Loudoun Medical Group, PC was last updated on October 28, 2022. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 3 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.