Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Mallory Sin, LDN, RD
Registered Dietitian in Boston, MA · enumerated 2013.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1821426826
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Registry record
Entity type Individual (Type 1)
Name Mallory Sin
Credential LDN, RD
Sex Female
Practice address One Joslin Place, Boston, MA, 02215
Phone (917) 825-0376
Enumeration date Oct 29, 2013
Last updated in NPPES Nov 27, 2018
Taxonomy & licenses
133V00000X Registered Dietitian Dietary & Nutritional Service Providers · License 1076733 (MA) Primary
RD · Registered Dietitian: A nutrition professional credentialed by the Commission on Dietetic Registration.
About the RD credential
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
How do I verify Mallory Sin's NPI record?
Cross-check NPI 1821426826 against the official CMS registry at npiregistry.cms.hhs.gov. This page mirrors the same public NPPES data with a monthly snapshot.
Is NPI 1821426826 active?
Yes, as of the latest NPPES snapshot, NPI 1821426826 is active (record last updated 2018-11-27).
Other providers at this practice address
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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2018-11-27.