Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Charles Michael Knudson, MD

Blood Banking & Transfusion Medicine Physician in Iowa City, IA · enumerated 2005.

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

National Provider Identifier

1144218926

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Registry record

Entity type Individual (Type 1)

Name Charles Michael Knudson

Credential MD

Sex Male

Practice address 200 Hawkins Dr, Iowa City, IA, 52242

Phone (319) 335-8147

Fax (319) 335-8453

Enumeration date Oct 6, 2005

Last updated in NPPES Dec 16, 2025

Taxonomy & licenses

207ZB0001X Blood Banking & Transfusion Medicine Physician Allopathic & Osteopathic Physicians · License MD-32575 (IA) Primary

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

Other identifiers

Identifier	Type	State	Issuer
0180018	Medicaid	IA	-
1180018	Medicaid	IA	-
33941	Other	IA	WELLMARK BCBS
46327	Other	IA	WELLMARK BCBS

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 Charles Knudson?

Charles Knudson is registered in NPPES with the primary taxonomy of Blood Banking & Transfusion Medicine 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.

Other providers at this practice address

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2025-12-16.