NPI Portal NPI Lookup & Verification

John Warren, MD

John Warren is a Clinical Pathology/Laboratory Medicine Physician provider (Pathology) practicing in Chicago, IL, registered in the NPPES registry with NPI 1104848563 since 2006. The credential MD stands for Doctor of Medicine.

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NPI 1104848563
Entity type Individual (Type 1)
Name John Warren
Credential MD
Sex Male
Practice address 680 N LAKE SHORE DR, SUITE 1000, Chicago, IL, 60611
Phone 3126959797
Enumeration date 2006-07-24
Last updated in NPPES 2007-07-08

Taxonomy & licenses

Taxonomy code Specialty Primary License State
207ZP0105X Clinical Pathology/Laboratory Medicine Physician Primary IL

MD — Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

Copy-ready billing details
Provider: John Warren, MD
NPI: 1104848563
Taxonomy: 207ZP0105X (Clinical Pathology/Laboratory Medicine Physician)
Address: 680 N LAKE SHORE DR, SUITE 1000, Chicago, IL, 60611

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1932197134 Shireen Ahmad Individual Anesthesiology Physician Chicago, IL
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Verify this record

Cross-check NPI 1104848563 against the authoritative CMS record: view John Warren on the official NPPES registry .

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 or validate an NPI number.

Frequently asked questions

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.
What specialty is John Warren?
John Warren is registered in NPPES with the primary taxonomy of Clinical Pathology/Laboratory Medicine Physician. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

Source: CMS NPPES (public data). Snapshot 2026-07-11. Provider record last updated 2007-07-08.