Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. Demetrios Spyridon Theodoropoulos, M.D.

Clinical & Laboratory Immunology (Allergy & Immunology) Physician in Onalaska, WI · enumerated 2008.

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

National Provider Identifier

1326299488

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Registry record

Entity type Individual (Type 1)

Name Dr. Demetrios Spyridon Theodoropoulos

Credential M.D.

Sex Male

Practice address 2727 Midwest Drive, Onalaska, WI, 54650

Phone (608) 782-2027

Fax (608) 782-6172

Enumeration date Oct 8, 2008

Last updated in NPPES Dec 14, 2015

Taxonomy & licenses

207KI0005X Clinical & Laboratory Immunology (Allergy & Immunology) Physician Allopathic & Osteopathic Physicians · License 44060-20 (WI) Primary

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

Demetrios Theodoropoulos is registered in NPPES with the primary taxonomy of Clinical & Laboratory Immunology (Allergy & Immunology) Physician. 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 2015-12-14.