Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Mr. Jan A. Pietrzak, MPH, RD, LDN

Registered Dietitian in Chicago, IL · enumerated 2006.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1346322146

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Registry record

Entity type Individual (Type 1)

Name Mr. Jan A. Pietrzak

Credential MPH, RD, LDN

Sex Male

Practice address 645 S Central Ave, Chicago, IL, 60644

Phone (773) 854-5852

Enumeration date Oct 20, 2006

Last updated in NPPES Jul 8, 2007

Taxonomy & licenses

133V00000X Registered Dietitian Dietary & Nutritional Service Providers 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.

Read the full guide → Validate an NPI →

Frequently asked questions

What specialty is Jan Pietrzak?

Jan Pietrzak is registered in NPPES with the primary taxonomy of Registered Dietitian. 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.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2007-07-08.