Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Margaret A. O'Callaghan, ANP-BC, WHNP-BC
Nurse Practitioner in Middleton, MA · enumerated 2007.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1881818110
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Registry record
Entity type Individual (Type 1)
Name Margaret A. O'Callaghan
Credential ANP-BC, WHNP-BC
Sex Female
Practice address Dys Ne Health Services, 33 Gregory Street, Middleton, MA, 01949
Phone (978) 716-1183
Fax (978) 304-4503
Enumeration date Apr 11, 2007
Last updated in NPPES Nov 16, 2018
Taxonomy & licenses
363LA2200X Adult Health Nurse Practitioner Physician Assistants & Advanced Practice Nursing Providers · License 234033 (MA) Secondary
363L00000X Nurse Practitioner Physician Assistants & Advanced Practice Nursing Providers · License RN234033 (MA) Primary
What is an NPI number?
A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.
Frequently asked questions
What specialty is Margaret O'Callaghan?
Margaret O'Callaghan is registered in NPPES with the primary taxonomy of Nurse Practitioner. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.
Is this the official NPI registry?
No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.
Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2018-11-16.