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NEPHROLOGY ASSSOCIATES OF THE MERRIMACK VALLEY PC
NPI 1700083433
Internal Medicine - Nephrology in Tewksbury, MA

Active since June 27, 2007CLIA 22D0710444 · Microscopy
600 CLARK RD, TEWKSBURY, MA 01876(978) 453-1811(978) 452-9111 Get Directions Write a Review

NPPES record last updated: February 7, 2024. Verified against the NPPES registry weekly; last sync: October 18, 2026.

Record update history: Feb 7, 2024, Dec 8, 2023 (2 updates tracked since 2023).

About Nephrology Asssociates Of The Merrimack Valley Pc NPPES

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

NEPHROLOGY ASSSOCIATES OF THE MERRIMACK VALLEY PC (NPI 1700083433) is a healthcare organization registered as a nephrology in Tewksbury, Massachusetts and active in the NPI registry since June 2007. The organization holds a CLIA Microscopy certificate valid through February 28, 2028 and lists Sarah Leduc, Practice Manager, as its authorized official.

NPPES Registry Identity

NPI1700083433
Entity TypeOrganization
Primary Taxonomy207RN0300X
Legal Business NameNEPHROLOGY ASSSOCIATES OF THE MERRIMACK VALLEY PC
Location Address600 CLARK RDTewksbury, MA 01876-1699
Mailing Address600 Clark RdTewksbury, MA 01876-1699 · (978) 453-1811 · Fax (978) 452-9111
Phone(978) 453-1811
Fax(978) 452-9111
Organization SubpartNo
Authorized OfficialSarah LeducPractice Manager · (978) 453-1811
Enumeration DateJune 27, 2007
Last NPPES UpdateFebruary 7, 20242 updates tracked since enumeration
NPPES CertifiedFebruary 7, 2024
✔ NPI 1700083433 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyInternal Medicine · NephrologyAllopathic & Osteopathic Physicians
Taxonomy Code207RN0300X
License✔ Licensed in MA · 37818
Definition
An internist who treats disorders of the kidney, high blood pressure, fluid and mineral balance and dialysis of body wastes when the kidneys do not function. This specialist consults with surgeons about kidney transplantation.
600 CLARK RD, Tewksbury, MA 01876
Open in Google Maps ↗

Group Practice 1

Group TaxonomyThis provdier is a business group of one or more individual practitioners, all of who practice with the same area of specialization.193400000X SINGLE 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)

Nephrology Asssociates Of The Merrimack Valley Pc is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

Clinicians Billing Medicare Through This Organization

4

Medicare enrollment records show 4 clinicians reassign Medicare billing to Nephrology Asssociates Of The Merrimack Valley PC, which bills Medicare for the services they deliver. Of these, 2 practice at this address. They are listed nearest first.

Clinicians, nearest first (4)

Douglas Mesler, M.D., MPH
Nephrology
NPI 1205827185
600 CLARK RD., 2FLR
Tewsbury, MA 01876
(978) 453-1811
✔ PECOS✔ Accepts MedicareSame address
Joseph Rossacci, MD
Nephrology
NPI 1699764449
600 CLARK RD
Tewksbury, MA 01876
(978) 453-1811
✔ PECOS✔ Accepts MedicareSame address
Ashish Mahajan, M.D.
Nephrology
NPI 1497974539
TUFTS NEW ENGLAND MEDICAL CENTER 750 WASHINGTON ST. #391
Boston, MA 02111
(617) 636-9606
✔ PECOS✔ Accepts Medicare22 mi
Neeraj Jain, M.D
Nephrology
NPI 1144425539
123 SUMMER ST
Worcester, MA 01608
(508) 363-5000
✔ PECOS✔ Accepts Medicare37 mi

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

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 for Provider-Performed Microscopy Procedures (PPMP) 22D0710444

Nephrology Assoc Of Merrimack Valley · Tewksbury, MA
Active · expires Feb 28, 2028
CLIA Number22D0710444
Laboratory TypePhysician Office
Certificate Effective DateFebruary 28, 2026
Certificate Expiration DateFebruary 28, 2028
Laboratory DirectorAshish Mahajan
Laboratory Phone(508) 453-1811
Laboratory LocationNephrology Assoc Of Merrimack Valley600 Clark Rd, Tewksbury, MA 01876
CLIA data matches this NPI record on: Address
This certificate is issued to a laboratory in which a physician, midlevel practitioner or dentist performs no tests other than the microscopy procedures. This certificate permits the laboratory to also perform 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 Nephrology Asssociates Of The Merrimack Valley PC's NPI number?

The NPI number for Nephrology Asssociates Of The Merrimack Valley PC is 1700083433. It was assigned to this organization in the NPPES registry on June 27, 2007.

Where is Nephrology Asssociates Of The Merrimack Valley PC located?

Nephrology Asssociates Of The Merrimack Valley PC is located at 600 Clark Rd, Tewksbury, MA 01876. The listed phone number is (978) 453-1811.

What is Nephrology Asssociates Of The Merrimack Valley PC's specialty?

The primary specialty registered for this NPI is Internal Medicine, specializing in Nephrology, with taxonomy code 207RN0300X.

Is Nephrology Asssociates Of The Merrimack Valley PC enrolled in Medicare?

Yes. Nephrology Asssociates Of The Merrimack Valley PC is registered in the Medicare PECOS enrollment system.

How many clinicians bill Medicare through Nephrology Asssociates Of The Merrimack Valley PC?

According to the CMS Revalidation Reassignment List (October 2026 release), 4 clinicians, all in Nephrology, reassign their Medicare billing to Nephrology Asssociates Of The Merrimack Valley 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. Of these, 2 practice at this address. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Does Nephrology Asssociates Of The Merrimack Valley PC hold a CLIA laboratory certificate?

Yes. A Certificate for Provider-Performed Microscopy Procedures (PPMP) (number 22D0710444) is associated with this NPI, valid through February 28, 2028. CLIA certificates authorize laboratory testing under the federal Clinical Laboratory Improvement Amendments program.

When was this NPI record last updated?

The NPPES record for Nephrology Asssociates Of The Merrimack Valley PC was last updated on February 7, 2024. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 2 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.